With colouring I think it will just be a case of practicing over and over until you assume a style your happy with. What I like to do is I find pictures of colouring and shading etc and scrutinise it. For example in the style im trying to adapt the shading on the hair contrasts quite a lot from the base colour and is blurred only slightly with the base. Occasionally other tones are used as well, I believe this is cell shading but im probably wrong. Anyway my point is; study your influences and try to mimic them, with study and practice you should be able to adapt your own technique personally I like to have a picture on my phone open for quick referral if I get stuck but with each time I try it out the colouring comes out much better than previous you could also look about on deviantart for tutorials on cell shading, I believe that is the kinds colouring your looking for (if I'm wrong just disregard all I've said about cell shading)
As for your lineart question, do you mean to literally hide it, or do you want ways to make it stand out less so you can bring more attention to the colouring?