Thanks for apologizing, Deatzh.
Sorry, I've been in L.A. for the last week, so I haven't been paying any attention to this thread. But I just want to state a few things for the record:
Delusions' colors are mostly the official colors, with a few minor exceptions (Like Bern's scarf / clothes on the chapter 10 cover.) Of course, you are free to interpret the colors any way you like in your own version. I have no problem with you using my lineart as a practice exercise for your coloring, and posting it here for critique. If it's good enough, there's always the chance that I'll use it. That is how Karla became one of my colorists after all, when she submitted her own colored version of chapter 4's cover.
Valenthesial, I'm not really much of a colorist myself, but I do know a little bit about it. It looks like you've put a lot of effort into those color pieces, and I appreciate that. However, there are some basic things you need to brush up on. Your shading needs a lot of work, it doesn't have any "depth" so it tends to make the characters look flat, especially on the skin tones. For example, Suspiria's leg in the pic from chapter 13 looks really bad because you've just added a solid line of shading to the right side; it makes her leg look flat, instead of rounded like it should look. Also, a big problem with most of your shading is that you seem to be using black for shadows. Generally this tends to create an ugly look... take a look at a lot of colorists and you'll notice that they use colors for shadows, almost never black. This is also why the scarf on the banner you colored looks kind of ugly, because of the heavy black shading.
Quite frankly, I'm no expert so I can't offer you much more than basic advice. The best advice I can give you is to go on the web and study up on some of the great colorists out there, and try to learn from them. It won't happen overnight, but I can tell that you have the fortitude to stick with it, if you keep practicing you will eventually get there. You have the talent, you just need more experience. I hope this criticism is useful to you, and please feel free to keep posting your coloring exercises here on the forum if you'd like.
As for people who have been rude in this thread, I will chat with them in PM about it. Please try to keep things civil.