I would take practice exams for the last 2 weeks up to the last week before the exam.
The final week, I would brush up on PAT and Reading Comp, but most of all, I would go over a "crib sheet" of details.
I would make sure i have all the formulas down, the reactions for O.Chem and the tiny details, like how many CO2 and ATP for the krebs, calvin, and other detailed stuff.
I've found that no matter how many times I seem to learn it, just 3 weeks later, I'm saying how many ATPs and CO2's do you get? Is that tertiary> secondary>primary >methyl or the other way around?
If you can cram these details the last week, I think may help.