I got all the tips at this forum so really want to give back...In short,
1. Do not wing it :) or under prepared even when you are currently living and breathing scrum.....I tried. It didn't work
2. Obviously, read Scrum guide from scrum.org...many times!
3. Do all the Scrum.org open assessments, including PO, DEV and Nexus.
3. Do practise time Mikhail Lapshin 80 Questions(FREE)