How do I flip an egg when preparing it "over easy"?
The best thing I've figured out about turning eggs is: do not do it too early. You need to wait for the cooked part of the egg to develop a strong texture before it will support its own weight. It's very difficult to turn a floppy, soft egg, where it's comparatively easy to flip an egg that has been cooked more completely on one side. I also use a relatively high heat, as this "crisps" the cooked surface. It also makes the egg more attractive.

The spatula you use can make a difference, also, though I believe this is minor. The spatula you want is a plastic one with a relatively thin, flexible blade. The really heavy spatulas tend to be too tall, in my experience, and push the egg rather than sneak under it.