The easy and hard questions seem to be evenly spaced throughout the test. So any questions I couldn't immediatly see the answer to or see how to work out, or saw how to work out but decided it was going to take too long, I skipped and put a dot next to so I could quickly return to it after I'd done all the quick/easy ones.
Then 15 seconds before the end of the test I filled in all the blanks with random answers. Worked for me.
Also, ask for the test to be started as the second hand on the clock hits 12 - makes timimg easier to work out.
Each to their own however.
Good luck.