Don't worry about sucking! Everybody sucks at new things. I've been doing this professionally for years and I still suck at tons of things. I work with people who are mind blowingly amazing and they still suck at stuff. They just have the diligence and patience to work on their craft until they don't suck as much. Art is a road that never ends, and the trick is to realize that and enjoy the journey.
Anyway, on the subject of color, check out James Gurney's posts about gamut masking:
http://gurneyjourney.blogspot.jp/2011/09/part-1-gamut-masking-method.htmlLike I said, I know full-time professional artists who struggle with this stuff, so don't worry about being perfect, just work on doing your best and improving over time. The more you work on it, the better you will be. Think about how you could paint the exact same picture at different times of day during different seasons, and you would use completely different color schemes. It could be warm, cool, dark, light, barren, verdant, etc. Think about not just the colors you want to use, but the colors you aren't going to use. Limitations are weirdly freeing in art. You can work wonders by picking two colors and just using different variations of saturation and brightness of those two colors. Watch Gurney paint with just red and blue:
When I've tried to emulate a style in the past, if I copy someone else's style exactly, I don't feel like I've achieved much. It makes for great practice, to figure out how someone did something cool, but I only do that kind of stuff for personal studies. Really interesting things can happen when I try to take ideas from art that is way beyond my skill level or interest, though. I had a lot of fun recently on a project where we took a lot of inspiration from rococo furniture, which is super ornate and takes unbelievable craftsmanship to create. When that inspiration was filtered through my own perception, limitations, and all the other inspiration I've accumulated over the years, something unique came out.