You shouldnt be afraid to experiment with colour. You best shades will be purples and blues. My favorite to add to darker skin tones are metalic shades. They really make the darker shades in the smokey eye effect pop. I also love doing smokey eyes with a bit of a pink or a blue to them to bring out a fun side to this look. It can get very serious if you let it but on the whole though you can get away with alot of playing around. Dont be afraid to test all your colours on yourself. Its the only way you will know what really works.