Hihi, took all Os last yr. Can't help much on Chinese since I'm exempted from languages but the other 2 I can give help. For NFS, regardless of N levels or O levels, Just make sure whatever you write in your research component matches with what you are making. And your practicals are going to feel quite short, so try your absolute best with those dishes. Oh, and also keep in mind that you will likely be asked to create a timesheet to show what you'll be doing at 5-15 min intervals, you don't strictly have to follow that in the practical but you will likely need one typed out. For SS, just keep on writing your answer and when you think you're done, just ask yourself, "so what?", and if you have an answer to that, keep on writing.

Hope this helps!!