Rule #1: Do a Lap Before you Commit
This one is obvious, but there's nothing worse than getting to the end of the buffet line, and having to balance a nice piece of Fillet Mignon on top of a pile of iceberg lettuce and industrial ranch dressing. Don't feel awkward about cruising the entire layout before you pick up a plate.
Rule #2: Focus on the Expensive Stuff
That's one of the beauties of the buffet, right? It's the same price if you eat only bread or only meat. Have another steak. Try some fish. If you don't eat meat, hover around the cheese or the sweets. Don't be shy.