So let's say I want to be an artist (illustrator) who focuses

You learn as you go man, stop worrying about what you don't know yet, you'll find it out as you get better at drawing. Just focus on drawing fantasy stuff and look up references constantly.

>>2840016
If you learn how light and color works at a fundamental level you can approximate any material, and if you want it to be really accurate, then that's when you find a reference. You don't need to learn it all at once.

>>2840016
google muddycolors building basic portfolios.

It's a blogpost from Greg Manchess where he goes over exactly this topic in detail.

>>2840016
For rendering materials there's How to Render, everything else is about context and effort. You can draw fantasy by slapping generic pauldrons on people with pointy ears as well as thorough research on trees, architecture and armor.

>>2840016
I'm also a fantasy artist wannabe. Sometimes I take screenshots from video games and study them. There's a lot of material out there. Even things like magic the gathering cards can give me ideas. It's okay to try to recreate someone else's work just to learn how they did it. It's really good practice. Also the Dungeons and Dragons Monster Manuals have really awesome artwork and ideas in them if you can't come up with anything. Don't try to learn everything at once or you'll overwhelm yourself. Oh also watching speed painting on YouTube can help you learn too if you really pay attention.

>>2840016
Sounds like you might be missing the forest for the trees. Ruan Jia kinda renders everything in the same sort of rock-like material. Not ideal I guess, but not a big deal, since the stuff that matters is being taken care of.