I feel that for reading comprehension, you really need to develop your own strategy. Some only skim the passages, while others read every other sentence, while others read the entire passage. What works for one person, may not work for you. I find that reading the entire passage works best for me and usually gets me 100% on reading comprehension.
For sentence correction, I highly recommend getting the
sentence correction book from Manhattan GMAT. It really is all you need.
For critical reasoning, have a look at
the critical reasoning from PowerScore.