Definitely read the passage first. What you want to do is get down a system of using your scratch paper to map out the passage so that you can accurately find answers when you get to the question.
Write down the paragraph number, and then write down a key topic word or phrase (the shorter the better). You might want to jot down a word or phrase or two more, but be careful not to write too much because it can eat up your time. Avoid jotting down details that you can just jump back and find with a good topic word.
The key is to practice enough that you are fairly confident in this system. In my opinion, going straight to the questions could be disastrous because if it doesn't work right, you'll get flustered and will end up stressing over time and will get even more flustered. This'll make it tough to focus. Try practicing the key word method.
Good luck!