The most basic e/s combination I ever learned was to use the lightest shade as highlighter, medium shade on the lid, and the darkest shades in the crease or as a liner. However, as you look at the FOTDs here, you will see that you can really do anything! You can make many different looks with one quad. Play around with using different e/s on different parts of your eye and see what you like the best.
That's what I do, then if I'm really bored, I'll take a picture of it with my digital camera to see how it looks to others.