I have dark brown eyes and tan skin also. Whenever I wear brown/natural eye shadows, I wear almost nude gloss with a hint of pink. Don't wear anything with glitter or silvery sheen, as I am guessing that your lips are probably about the same color as mine also. The gloss will dry out and either make your lips looks you've dipped them in a bowl of glitter or that you've coated them in aluminum-colored gloss.

If you don't want to take attention away from your eyes, just make sure that the gloss you wear isn't too shiny or try lip stain instead. Neutrogena has very affordable natural-colored glosses. If you have a little more to spend, try a lip stain/gloss combination. You can purchase good ones at stores like Sephora or MAC.