Oh, hi! Glad to hear that you're interested in making your own NES visuals! Yes, I do write custom software in 6502 assembly. I'll agree that learning the programming language and hardware specifications requires a LOT of patience and persistence. Here are some ideas for getting started with NES visuals:
1. As a way to get started quickly (i.e., without programming), you might like playing with graphical ROM hacking (with YY-CHR, for example). This is an easy way to become familiar with the graphic format of NES games. Check out romhacking.net for more information on ROM hacking.
2. NO CARRIER's glitchnes and NESFlix and blargg's litewall are awesome NES visual programs that require little to no programming experience and are well documented. The great thing about these ROMs is that they're really suited for visuals, and you'll be able to add your own graphics using a program like YY-CHR. I tried out NESFlix recently, and I was able to make a ROM from an animated GIF in under 30 minutes (!).
3. If you're looking to make truly custom visuals and willing to devote some serious time to learning 6502 assembly, I would recommend the NES programming tutorials on the Nintendo Age forums. (In my opinion, NESDev is not the absolute best place for beginners.)
Best of luck to you!