A score of 300 probably indicates a need to work not only on strategy, methods, techniques etc. but also the fundamentals as well.
So you may need to go back a step and make sure that you have the fundamentals down and then build up slowly. It can be frustrating to see all hard questions at a point like this. Maybe you can do some of the earlier questions in the book "Official Guide to the GMAT 12the Edition" by GMAC. The earlier questions can be better for learning and building confidence.
You also do need to work on your methods. I recommend that you write out step-by-step what you do at the beginning of each type of question: Critical Reasoning, Reading Comp, Sentence Correction, Data Sufficiency and Problem Solving.
The first steps to each question really should be the same and once you have broken down the question you can then react to the individual differences in questions.
Here is an example:
For Data Sufficiency, first read the question stem and the statements. Next, write down either # or y/n for the "specific value" or "yes/no" type of question. Then write down what the question is asking. If there is a fact in the question stem such as "x is an integer" or "xy = 222" then write that down as well." Now decide which statement to evaluate first and so on...