Make sure to absolutely know everything that is on your sectional and terminal charts, and where to find any sort of information you might need for your flight. Airspace, aircraft limitations, frequencies you will need, etc.

This stuff is important for you to know, so make sure to study it. The rest of the stuff is pretty much what you should have known when you took your written test, and if you forget something you can always look it up. But like I said, when you're up in the air you can't look something up, so make sure to know anything that may come up while you are flying.

Also, make sure you clearly communicate with your examiner and know what is expected of you.

Not doing that is how I failed my checkride