COLOR WHEEL EDUCATION!
Let's talk about a color wheel. This will help you decide what colors in eyeshadow will make your eye color pop!! (btw - this color theory works with EVERYTHING -- designing your house, painting, clothes and jewelry ;) ).
Now, anyone can wear ANY color eyeshadow. There are NO rules. But if you're looking to REALLY pop out certain colors in your eyes, this is how to do it.
Find your eye color on the wheel. The colors directly across from it are the colors you should use to make your eyes pop. The other colors to look at our the ones RIGHT next to your eye color - they won't have AS dramatic effect BUT it will still look great. So - remember -- OPPOSITE and ADJACENT!
If you have amber colored eyes. (so brown / hazel / some yellow) If you really want to pull the yellow out, use anything in the "Violet" or "Red Violet" scale. If you want to make the brown really pop, you use anything in the "Blue" scale.
Now I have blue / green eyes. If I use something on the more "Orange" scale it bring out the blue in my eyes. Burnt Reds bring out more turquoise / gray.
I hope this helps you choose your eyeshadows in a way that helps to accentuate whatever color you're trying to pop! If you need help, drop your eye color below and I will expand on details ;)