Id suggest some fartlek type training.
When going out for run's along the street try a mixture of run/sprint/jog between each lamp post/tree. This way your not just working on your aerobic systems but also training your anaerobic systems.
Technique also makes a great difference to bleep test scores. Best way is to sprint fast through the middle of the 20m, and slow down to almost a walk for the corners when you turn. This means you use momentum in the middle for speed, and use less effort to stop that same momentum for the turns.
Way back I was advised by a DS to run steady pace all the way through the shuttle, and work hard on the turns. This is bollocks. Dropping that steady-pace technique, and switching to sprinting through the middle & turning slowly, I jumped from getting level 9 to level 11.
Not a great standard test of fitness if technique can make that much difference, but there it is.
Maximizing Your Score
The beep test is a test of fitness, and is used as a measure of your aerobic capacity. It is not something that you would normally train for, as you would usually be doing the training for your specific sport and using the test to determine if you have reached your training goals.
However, the test is also commonly used as an important selection criteria for some sporting teams or jobs. Therefore many people need to train specifically for the test in order to reach a desired score.
Ideally, the test should be a true representation of your aerobic fitness. However, due to the nature of the test, there may be inaccuracies and you may not be reaching the level you have the potential to. I see that there are three main areas that can be addressed to maximize your beep test score: mental toughness, pacing strategies and physical conditioning. Depending on what level you are at, one or more of these can be used to help you achieve your potential in this test. Do Physical Training
If you really want to significantly improve your beep test score, you need to do some aerobic type training. You cannot avoid it, you will have to do some hard work. This would include some long slow running with some interval training. Prepare Well
You should be physically ready to perform the test. You should have recovered with at least 24 hours since the last heavy training session, and be free from injury or illness. Make sure you hydrate well before hand (see pre-exercise hydration), and have a light meal 1-2 hours before the test. You should also feel comfortable, by wearing loose clothing and by having firm fitting footwear with a good grip. You should also perform a light warm-up before the test. Be Mentally Tough
The beep test can be a mentally tough test for some, and some good improvements can often be made, without any change in your base fitness, by a more positive state of mind. Pushing trough the pain barrier may help you reach a higher level. Use Sound Technique
Using an efficient turning technique you will minimize any excess energy wasted during the turning phase. As you come in to the turn, time it so that only one foot just touches over the line, and turn sharply, not following a wide arc which will mean more distance traveled. You should drop your hips slightly as you turn, and push off strongly for the first few strides to get up to pace. When you get near the end of a level, try to be on time with the beep, and step up your pace straight away. Run efficiently to conserve energy - run with your shoulders relaxed and breath deeply and smoothly. Use Pacing Strategies
Also without any change in aerobic fitness, you may be able to improve your score by pacing yourself so that energy is not wasted from end to end. Try and stay relaxed, quickly getting up to the required pace. Running at a consistent pace will be more efficient.