One of the first things I do with new clients is ask them what they know about the GMAT. Or more importantly: What the GMAT tests and how it tests it?
The GMAT is a test of executive reasoning skills --- not blended Math and English test. Why that's important is it tells you how you should attack every question: by using your reasoning skills to
1) gather and maximize the information you have
2) define exactly what "your job" is to reach the right answer
3) find the most efficient and accurate way to do that "job"
If one of your major problems on the GMAT is timing, then this might be important for you. The easiest way to illustrate it is by a couple of examples:
1) When you're working a CR question, do you read the prompt first or the question first? CR questions have lots of different angles and the angle each question comes from is the key to creating focus in your reading of the prompt and the answer choices. So the key first step is the read the question itself (before the prompt). That narrows your focus and gives you the right 'lens' on the prompt. It's silly and inefficient to be focusing what the prompt is using as core assumptions when the question what you to assess what would strengthen the argument.
2) In a SC question, what should you focus on in your first read of the answer choices? It's the change points between them. For example, if some are plural and some are singular, then you can quickly find a way to eliminate as many as 3 answers out of the 5. If there's a shift in the relative positioning of a subject and a modifier, that's another key change point between the answers. Again, it's a quick and direct way to eliminate some answer choices and narrow your focus to only a couple of choices.
The key point here is that your job is not to holistically read a passage or prompt and analyze everything about it before you look at the answer choices. Your JOB IS to choose between the answer choices -- if something DOESN'T change between the answer choices (like pronoun you don't like or a verb that doesn't sound right to you), then it's IRRELEVANT to your focus on choosing the right answer.
It may seem like a simple point, but you'd be amazed how many test-takers let this get away from them. Narrowing your focus (by gathering everything the prompt and answer choices give you) is one of the important way to solve timing problems on the test -- by avoiding time wasted on doing more than you have to answer a question.