Some strategies that I've been following on GMATPrep practice tests. They seem to work very well for me (at least from "time-saving" perspective).
CR:
1. Read the statement/passage carefully and then try to think of the unstated assumption (however it's important not to waste more than 5-10 seconds trying to think of assumption). If it's a "weakening" question then you have to choose the answer that does one of these 2 things: (1)pokes holes in the assumption (2)provides an alternate explanation.
2. If you're stuck between two choices, pick the one that (1)does not go outside the scope (2)
is COMPLETELY error-proof (3)is mild (non-controversial) in tone.
RC:
1. Always read the first question before reading the passage.
2.If it's a Science based passage, follow the variable-speed reading approach (mentioned in PR) and stay within 2-minute limit for reading.
3. If it's Business/History/Social Science based passage, read more carefully and stay within 3-minute limit.
4. After reading a passage, pause for 10 seconds and think about the "main idea" and "structure" of the passage, then move on to answering questions. This extra step will help you answer general questions faster.
5.Don't spend more than 8 minutes (including reading and answering questions) on any passage. It's very
very important.
SC:
1. On every SC question, first look for errors in the underlined part and then scan through answer choices, looking for differences there. This will help you identify any additional errors that you may have missed the first time. It's very important to do both of these things and only then use POE.
2. Never spend more than 2 minutes on any SC question no matter how hard it is.