It's not tricks that get you a high score, it's getting answers right.
My last week before the test, I drilled through about 200 problems on
magoosh that were mediums. It was a good confidence boost and I really focused on reading the question, understanding it, and solving it mistake free. For the last 2-3 days I did nothing other than write a single awa practice essay. Veritas, Manhattan,
magoosh, and especially the official gmat books, will all be plenty good to practice.
I can't think of a single "trick" that I used. The only "fancy formula" I used was a single 30-60-90 problem. Unless you are at a q50/51 you will be pretty unlikely to see anything that can't be solved with basic knowledge and good techniques.
Also, not only does solving a bunch of mediums correctly reinforce good habits, going into the test confident and calm can have a a surprising effect on your performance.