Maybe I was lucky, but out of the 7 rides I've done, I've had the same two DPEs and one FAA inspector (CFI initial). I would ask your instructor if they know of areas the DPE likes to bring up. As a rule, I ask the DPE I send my students to if there is anything in particular he or she should review. Talk to some of the students who have had rides with the guy/gal you're going with. But above all, be confident, but not arrogant. Not scared, but collected.