oh woah.... O-levels.... seems quite distant liao...
But some quick tips for students facing pre-exam stress...
1) do mind maps (as mentioned by some forumites)
2) should you choose to "spot" questions, do try to at least go
through briefly all the other chapter/topic summaries or
teacher/lecturer's slides. coz in the event that your "spotted" qns
don't show up *touch wood*, you at least have something (in your
last minute memory bank) to write about...