Good advice from all above. Keep in mind that there will be 3 people on the day of your checkride who want you to pass, you, your CFI, and your DPE. A temporary certificate is much more satisfying to the average examiner than a pink slip!
On the oral, answer the questions you are asked. Don't venture off into unknown territory unless you are absolutely sure of yourself. Keep your answers to the point. Know where to find the information if you don't know, don't guess- this is an open-book test, use the books if you need to!
In the aircraft, listen to what you are being asked to do, don't be afraid to ask for clarification. Make sure you clear the area before maneuvering. I would recommend you talk your way through what you are doing, if the examiner is not sure what you are up to, letting him/her know what you are thinking/doing may help to keep you on the same page.
Last but not least, don't forget the safety briefing! More than one ride has stopped before it started because of this omission. Seat belts, doors, emergency equipment.
Come in confident in your abilities, you should know your stuff, this is just a verification exercise!!
Good Luck, Tony