I feel that everyone has their own strategy and after a few rounds of practice or trying different ways, they find what works best for them. What I do is read through the entire passage, but super fast, just to get an idea what it's about. And usually as I'm speed reading through it, key points just stick out that help me remember that exact point or where it was in the passage. (If that makes sense) So then I go to the questions, and start with one, if I know it answer it or do the "search and destroy" method where I go back and find the answer. ( It takes a shorter time to search since I did the speed reading before). Also I think it's an advantage to speed read before because there are questions that aren't fact questions, but more of understanding the passage questions, that might be difficult to find if you start of with "search and destroy" right from the beginning.
Also I remember reading a post where the person would do this: Read Q 1, read passage till you find answer. Do Q2, if already read it thus far, answer it or keep reading till you find the answer. Do Q3, if already read it answer question otherwise continue reading the passage. ----I have never tried this before but would like to try it.
Good luck