One of the most difficult GMAT scenarios I have faced followed from asking myself this dreaded question, "What can I do after I have studied hard for months and my practice tests are the same score that they were in the beginning?" I have consulted similar forum topics from test-takers, but would like to present my own outlook on what I myself am prepared to do in this situation. If you have already Beaten the GMAT, I encourage you to share what your turning point was after crossing this particular barrier.
1. Define improvement. Practice tests are the benchmark to define approximately how well a test-taker will perform on the actual test. After learning test concepts and doing practice problems, a person should theoretically improve on his or her test score, which is measurable. As we know, this isn't always the case since the GMAT tests deeper than mere recitation.
Defining 'improvement' in terms of your studies is the starting point to connecting practice into a tangible score result. The closer you track the metrics on performance in different problem types will help close the gap between days of practice and a resulting score increase. This implies you have already differentiated each of the major problem types and the frequency of their appearance on the GMAT. Preliminary understanding of GMAT scoring is also essential.
2. "Practice doesn't make perfect. Perfect practice makes perfect" Perhaps you have heard the mantra "10,000 hours creates an expert." This adage describes individuals who after years of playing golf (Tiger Woods), composing (Mozart), or programming (Bill Gates) became the best in his or her discipline, but not all practice is the same. Deep and meaningful practice is much more significant than one which is lengthy and unmonitored. A mindful musician can perform 3 months of practice in 3 minutes if he or she is critically aware of the practice, making corrections and connections between patterns that are more likely to be stored in memory. This is the topic I have found discussed the most in my review of past GMAT students who faced our problem. I believe this is so for a good reason, because it is often the biggest problem and most difficult to face, but also the most beneficial.
An analogy can be taken from Data Sufficiency problems on which it is so important to rephrase and define the actual problem. Einstein himself, when asked what he would do to save the world in 60 minutes, said he would be to spend 50minutes first understanding the problem. Because everyone studies differently the problem in your studying is not the same for everyone. Maybe you need to read dozen of books on a single subject before you pay attention and let yourself get it. Perhaps you need a tutor or someone else to break apart your study habits or present a new approach or strategy. Don't always think that what works for someone else will work for you. Instead use other's experience as a starting point, but I encourage you to devote the necessary time to critiquing and mapping out your technique.
3. Strategy. Create a plan and implement it. If your study plan up till now hasn't garnered the results you desire (and you are reading this after all) than change them. Or throw them out. Also consider that you may be studying too hard or too much. Consider how much time you will need based on your progress so far and don't rush yourself. Yes there is a window for applications and timing is important, but you cannot rush brain development (technically described as myelination if you are interested in learning more). Compare developing your brain to developing a muscle group, such as your biceps, in the gym. Rest and recovery are central to body-building because this process is where the muscle actually grows where as in the gym you are stimulating growth by overloading the muscle to handle resistance. Professional body-builders also incorporate a period called 'deloading' where they take extended breaks from lifting (over a week) to allow the body time to catch up on rest and recovery completely. The brain operates slightly different, but this principle still applies.
When you are ready to create your strategy, first examine your goals and the reason why you need a strategy. A plan will help you achieve the rational utilization of your scarce resources: time, attention or focus, patience, etc. (basic economics). The overlying goal for your plan stems from how well you set your objectives, which you can define in many ways, both broad and narrow. Examples could be: I want to memorize every square and cube number from 1 to 20 by one week from now, I want to create a list of every math topic and the general methods for each by next week, I want my success rate on sentence correction to improve from 8/15 to 13/15 by the end of the month, I want my verbal to improve from 36 to 40 then to 44 on my next two practice test. The act of identifying your goal and writing them down not only gives you insight, but registers accountability on an internal and external level. Ideal goals (as taken from project management) are S.M.A.R.T., Specific, Measurable, Attainable, Realistic, and Time Sensitive. If you have taken your goal-setting activity seriously than setting up a plan to meet those goals will be much easier.
The next aspects you should focus on in your plan include what you need to study and what resources you will use to study. Fortunately these pieces are easy to assemble because you are able to define areas of weakness through diagnostic and practice tests, and receive recommendations on the quality of different preparation resources. Here again it is worth mentioning that if your past strategy was to read a bunch of books and do a bunch of problems than perhaps this isn't the best approach this time. Instead you want to specify what you will take away from each lesson and practice problem. A plan may consist of "I will do 10 problems from 3 sections every day and review them. I will then repeat two more times any questions that I got wrong, took too long on, or was not comfortable with." I would suggest including a variety of problems in your practice in order to best mimic the actual exam.
4. Performance under pressure. As you probably already know, so much of the GMAT is about trying to make you crack under pressure. From the check-in at the test center to differences in meaning between "most" and "many", the test is certainly stressful. In contrast, your studying, however intense, will unlikely re-create these conditions. This doesn't mean you should create stressful study habits, but rather that your mental state (both conscious and unconscious) should be identical in your studying as in your test. You have been thinking the same thoughts about how much this test means to you for hours, days, weeks so why do you need to think about them during your study or test taking time? Instead, try to be aware of what you are thinking and feeling and find a balance between relaxing on the test and feeling the pressure during your practice. There are a lot of tips to pick up in decreasing test anxiety because it is very important (don't wonder if the question is experimental OR leverage this knowledge, leave each question behind completely when you finish it, don't try to guess the level of difficulty of the question, visit the test center ahead of time, practice with the laminated pad...). Your emotions have tremendous impact on thoughts! Understand them, and unlock your inner zen master. While it may be difficult to face, listen to your inner voice, you will almost instinctively know the way that you too will Beat the GMAT.