I'm reaching a point where I'm feeling I'm Stagnating a bit regarding lineart. I don't want to increase my canvas sizes more than I have to, usually sitting around 1200x1000ish.

Are there any artists who have tips for what I could do to improve my lineart? (Maybe color theory too? Since I think I get it, but I always get this feeling my colors are too muted and could use some tips on how to brighten them up.)