@lauraa Steal it :)! I had a teacher who is really good at color and told us that when he was working for a newspaper way back he had to produce a lot of paintings quickly he didn't have time to mess with color so he took successful schemes from illustrations he liked. Eventually he really developed his "color muscle" and didn't need to do that any more. You can't really plagiarize a color scheme, haha, and by using something you know works, you can learn faster. (The values and/or mood of the referenced piece should be similar to what you are going for though)
Also limiting the number of colors makes things more harmonious, applying a transparent colored "wash" layer over everything using the multiply or a blending mode of your choice also can bring things together. Also working in complements with a ratio of 60:40, 70:30, or 80:20 works well usually. Many successful artworks I find are usually complementary/split complementary or analogous.
My mind works color over value so agree with @Chip-Valecek and sometimes I often go straight to color studies and work 'reverse'. I also would suggest thinking of the mood you are trying to acheve and working based on that and the psychology of color (Red=hot, passion, pain, romance, adventure. Blue=cold, tranquil, water, clean, sad. Green=life, nature, sickness, radioactive. Yellow=Sickness, joy, warmth, sun, light. etc.)