Know the practical test standards and you can't fail (the ground portion anyway). That's all they can ask you so if you know all that stuff for the ground eval, you'll do fine. Same applies for instrument, commercial, etc.
For example, on my cfi oral I had my PTS out the entire time with notes I had made of where to reference certain regs or diagrams. The instructor said he liked it and showed that I was prepared.
Having said that, the examiner will know more than you, and if you are doing really well, they will ask you something you won't know to see if you can think on your feet and look up the information or figure it out. Don't stress about that and just learn from it. The examiner isn't trying to make you fail, they're trying to teach you something.
Good luck!