@M1rage hmm there’s Probably alot more qualified people than me to help answer this but I hope what I say can help.
Firstly id check out @KaneDriscol youtube channnel ( https://youtu.be/2TyqblVHif0 ) Hes got loads of videos going over character types of different world settings and creating your own homebrew content. And just videos that serve as a great reminder to mechanics of ICRPG.
Next up, what you make doesn’t have to be perfect. You’ll always slip up with a ruling or making an ability way too strong or weak. Its important to do a quick simulation with yourself and also listen to what players using your Types comment on or say feels bad or good. See if these things make you want to make changes or if you have a real reason for why this ability is supposed to stay feel like it does
when making a type I like to stick to a frame work
3 starting abilities (these should follow the core theme of your type)
3 Starting loots (These should stick to theme and each loot should compliment a corresponding starting ability)
1 ever stronger milestone(very basic, +1 stat, +d100 coin, =1 spell and +1 of something that Type unique )
6 unique milestones (these dont have to be direct upgrades that make abilities stronger, try to compliment your type more with these. If you are relating them to abilities and loot follow a 2/2/2 theme so things stay varied)
3 mastery (mastery is normally a major upgrade to a starting loot or ability, remember it normally takes 20 nat 20s to get here so be grand, even make up unique mechanics if you want. Another thing to remember is that an icrpg , if a Mastery ability is tied to a Starting Loot you dont own, you Automatically get that loot when taking the Mastery. )
and i normally like to have the abilities relate to each other in some way, not just as specific upgrades but as awesome combos too. As much as its fun to see you’re main ability get stronger , In my experience Having types able to do many unique combos feels way better to the player and good for your own creativity. Think Side-grades not just Upgrades
Theme is really important, I cant take 100% credit for these types because alot of it comes from me looking at something that already exists and translating it into table top. Try picking classes from other systems or character tropes from your favorite movies and shows. Even a favorite species like a fairy or werewolf can be types. This can help you with coming up with fun ideas and practice theming, learning what to cut and what to keep in the Type.
If you can, work with and get advice from others. Theres so many creative people in this forums that will be willing to give tips and ideas, and honestly I have friends who aren’t even deep in the hobby giving me ideas too. having another voice besides your own giving input and ideas is a great boon to the process
finally just remember its all for fun, Make them powerful, make them weak, make them weird. its all for fun and enjoyment so the most important question to ask at the end is “Does it feel Fun?”
I hope this loooong response helps at all, and please post any Types you make so i can see and play them too!