One thing to make sure you do: Answer all the questions you know (or at least feel very confident about) in the block first, marking the ones you're not sure about along the way. Then come back to the ones you are not sure about at the end of the block.
Don't waste too much time trying to figure out a question you aren't sure about in case that makes you miss out on the ones you are more likely to get.
Good luck to you!