My #1 tip:
Mark and move on.
See a question you don't understand how to compute right away? MARK. and go to the next.
The key to QR is time management and grabbing every easy question, since all points are equal. Save all the hard questions for last.
Also, be familiar with using the calculator with a mouse, and don't be afraid to use it to double check.
Work on bootcamp's QR sections, it can be rough but you'll see a pattern of problems and it's good to know a gameplan on tackling these.