I'm just gonna jump right in, and get started!
CHARACTERS NEED A PURPOSE
Although, it seems like a no-brainer, sometimes it's actually easy to neglect your character's personalities. You end up making them extremely one-sided or just shallow. Many times, this can be due to making self-insert characters. I know, because that was the origins of my story. My main character, name Carmondy at the time (now Carmandy because it looks/sounds better) was a self-insert of me. Meanwhile her love interest, an owl-turned-elf character named Fukuro, was modeled after Adam Young/Owl City. When it comes down to it, I was just telling the story of how much of an Owl City fangirl I was in the most intricate way possible. This might of worked, if I was any good of a character creator and writer, but both Carmondy and Fukuro ended up flat and basically had no purpose, other than to fulfill my fantasy of smooching Adam Young. There was no real meat to the characters and it was basically just me and Adam in cartoon form.
BE INSPIRED, BUT DON'T BE A THEIF
The artist Mark Crilley talks about this in one of his videos, and it's something I had to learn to understand. When I first created my fantasy world, I used anime as my key inspiration..namely, Hiiro No Kakera and Fresh Pretty Cure. Using the anime as inspiration isn't bad, but I just began pulling things straight from the anime world and injecting them into my world and characters. I had male characters that I posed as bishies (anime version of a pretty-boy), I had weird outfits that were weird for the sake of being weird, every character had some strange, unnatural hair color (some still do, but not like they did) and there was a lot of Japanese influence, in a world that wasn't Japan-based. This is what I mean.. here is the some of the character of Hiiro No Kakera, while here and here are two of the first characters I made. These characters just weren't me. They simply just looked like what I thought a bishie would look like. Being inspiring by something mean you us eit as fuel to create your own thing, but it doesn't mean you copy every little thing you see. You can start with what you know and add your own details to it.. make it unique to you! ....but speaking of unique...
DON'T GO OVERBOARD WITH THE UNIQUENESS
I think it's just an automatic thing to do when you're just starting to create your own fantasy world. You want to make sure it's uniquely you, that it has names and cultures and languages never before seen...but all too often, it can go overboard. I tried too hard to be "unique" with my character's names and it ended up making things weird. Honestly, I think the line should be drawn when you have to provide a “guidebook” for how to pronounce character and location names, or it looks and sounds awkward. Having one or two that are strange and quirky isn't bad, but try not to give every other character a mystical fantasy name. Originally, I had characters like Valintive Valeos, Paradox Safecaster, and even Orange Mcapple. While these are all interesting sounding names, and definitely say this is a world unlike our own, some of them are weird to pronounce, awkward to put in dialog, and/or sounds just plain silly in context. To fix this, I think taking real-world names and spelling them differently or mashing them together (Rani+ Vanilla = Ranilla, or Lisa = Leasa), using names for things in a specific language(while Gaelic and latin are common, or elvish, there is also Hindi, Swahili, French, or whatever you like!), or swapping out letters (like replacing all the i’s and e’s with y’s, Ken might become Kyn) can help.
USE NAME GENERATORS DELICATELY
I think we've all been there. There's a myriad of name generators, specifically for oc's out there, and some just for fantasy. However, while it helps get your creative juice flowing, many times these names aren't the best to use as official. To make my point, my character Paradox Safecaster got his name completely from a name generator without editing...and while there's no harm in giving a character a name of two words mashed together (I mean, Luke Skywalker, anyone?) it just didn't fit the world I was creating. The word "paradox" comes with such a strong image, it would make sense to use it as the name of a spaceship or a futuristic robot... but for a neo-victorian elf world, it wasn't working. While name generators are great to help you get ideas, don't be so ready to take the suggestions word for word, letter for letter. Try changing up the spelling of a prompted name from a generator (which is what I sometimes do now) so that everything lines up and it feels like one solid fantasy world. So all of that being said....
KEEP ALL YOUR FANTASY NAMES/LANGAUGE CONSISTENT
First off, if you're trying to create your own fantasy language, then MORE POWER TO YOU because that is pretty admirable. Good on ya!Of course, most choose to write in their native tongue (or just English) but the point in what I'm saying is still the same. Try to keep consistency with the names of nouns and also, if you use any words for the character's language. For example, I use a lot of "iq", q's, and z's in my names, having places like Venziq Port, Windchestiq Woods, Port Westiq, and the Gravroq Tunnels, while the elf races are Afari, Lunari, Dokari, and Vulpelves. Originally, though I just named things and characters based on if I found the name cool or if it sounded "fantasy" enough. In being conscious about names, I feel it helps to establish the culture/s of your world and helps you get a grip on naming other characters and places in the future because you will have a sort of pattern to work from.
KEEP ALL OF YOUR CHARACTERS CONSISTENT AS WELL
This is something I still have to work with. Of course, when you are making a comic or a series of illustrations for your characters, you always have to be mindful of making sure the characters look the same from every angle (thank God for character model sheets!) but you also should keep them consistent in personality/aesthetic as well. For example, all of my elf races wear some sort of neo-victorian/steampunk fashion, but each have specific colors and symbols/objects pertaining to them. The Lunari live on and around the water and wear mostly (pastel versions of) silvers, greys, blues, greens, tans, or white. Meanwhile, the Vulpelves live in treehouses and wear colors such as reds, oranges, greens, browns, coppers, cream and black, with metals, machinery parts, and local flora as fashion accessories. Key characters of these elf races will pull from these "guidelines" to get a sense of consistency among my characters.
DON'T FOCUS ON UNIMPORTANT DETAILS EARLY ON
I'm a very detail-oriented person when it comes to my art. While not a perfectionist, I do like to put thought into the details of a drawing or story, so that the viewer/reader can have a little fun experiencing the art. It's very good to have even the most minute of details ironed out. I mean things like... what material your character's pants are made of, their favorite toys growing up, types of armor used by the army, what specific type of guns, swords, etc weaponry their military uses, down to the brand of bullets or metal. It's true, people will ask questions and you want to at least TRY to provide the (canon) answer. However, when you are planning out the answer to all these details...and your main story still has characters or places without names, plot points or holes that don't make any sense, and a lore/culture that is underdeveloped, try to focus on these things first. People will ask questions, but they will ask the big ones before they can ever get to the small ones. Readers/viewers are more likely to ask "How did they get all that treasure from there to there?" than they are "What does [character's name] use as make-up?" It took me a while to realize that no one is going to care about the intricate colors of my character's hair, as much as the story itself... until they begin to fall in love with the characters and plot. Once you have people hooked on your creations (or have them fully fleshed out), then I think then you can try to jigsaw all those little details together. Which reminds me...
DON'T LIMIT YOUR FANTASY WORLD TO REAL WORLD LOGIC
The first thing anyone will tell you, when you create a fantasy world, is that consistency is key. If you want your world to be completely otherworldly and say, have no gravity and a permanently purple sky, then this better always be true (unless the story itself is about changing one of those things). However, this can also work the other way. I mainly did this when creating the nobles who lived and worked in the castle, but I've noticed a lot of other world-builders do this with weapons or fashion. Basically, when I was creating my castle characters, I looked up real world castles, and the jobs one can have working in a castle. While it's always good to be inspired, I took things too seriously and tried to match up the real world jobs with my characters. Eventually, I realized it is okay to make up my own jobs and job titles, especially because this is fantasy. I've seen someone specifically say "OH my character’s culture is based off of Greecian and Roman culture, so, historically, they can’t have X-type of weapons" and I think that's just so limiting... unless you are doing historical fiction. It's a fantasy! Don't be afraid to make up your own things.. as long as everything is consistent it should work. This is why Steampunk is such a successful concept. It's Victorian or Edwardian inherently, but a steampunk character can still have a computer or a television or a car, simply because of the steampunk aesthetic and in how the object is designed/put together.
(APPROPRIATE) MUSIC CAN REALLY HELP
If there is one thing that I love to do, it's use music as a tool for/with my art. Naturally, I would find songs as I created my world, but I found out it actually helps a lot. Now, I don't just mean turning on the radio to the local pop or r&b station and listening to just anything while you work. I'm talking about having a specific type of music to listen to, one which helps to capture the feel, aesthetic, setting, and atmosphere of your world and your characters. For me, it's all about electronic music, or the action/adventure, romance, fantasy, and steampunk-ish sounding songs. Two great sources to go to for music inspiration is Two Steps From Hell and Audiomachine. Both artists have albums that capture a certain atmosphere (there is an album for a hypothetical romantic movie, one for a dark fantasy movie, one for a horror movie, etc) and pretty much all of these songs on any album can be found on their site and on Youtube. Other recommendations I would give is Sizzlebird, Port Blue, or AYoungScores. All of those can be found on youtube as well as others like FutureWorldMusic, Ivan Torrent, and official scores to movies/video games/tv shows. In any case, I really believe listening to the right music really helps. Try writing an action-packed pirate ship chase scene in silence.. and then try writing the very same action-packed scene while listening to this. If you're a good writer then it might be the exact same either way, but I believe music helps those like myself who have to be completely immersed in the scene and situation in order to write about or draw it. As a sidenote, I know I used pop and R&b as an example, but if that matches the aesthetic or atmosphere of your world or a certain character or something, then go for it! Find the genre that matches your world!LASTLY
DON'T BE AFRAID TO EDIT, ALTER, SCRAP, OR RETHINK YOUR IDEAS AND DESIGNS.
I rarely have a clever idea, so when the moment does happen, I make sure to capture it and never let it go. However, my clever idea, might not be as clever as I once thought. In the 5-6 years I've been working on my story, it's gone through 3 different titles, has lost and gained perhaps 10 or so characters altogether, character's names have been changed dramatically, and even the entire direction and plot of my story has been heavily edited 2 or 3 times. My main character, Carmandy, had a name change as well as a redesign twice. This is one of the things I've been doing right, that really helps me in world-building and character development. You can't get too attached to a story, especially in it's beginning stages. Things evolve the more work you put into them and you'd be surprised to see how many of your favorite characters and/or movies first started out. Ie, Disney's Tangled was first titled "Rapunzel", then "Rapunzel Unbraided", until Tangled was agreed upon. The character Eugene/Flynn was also heavyset with broad shoulders and a thick core in his original concepts. Even after stories are published and movies are released, characters undergo redesigns and wardrobe changes all the time. And that's it!
All of the things I've personally learned so far from doing my own world building, and/or learning about character creation in illustration class. Hopefully it helps and is useful!
Happy world building!