Dlab

DLAB
According to individuals who have taken (and passed) the DLAB, one can improve their scores by:
Having a very clear understanding of English grammar. You will need to know all parts of speech and how they work. You may wish to get your hands on a good college level grammar text book and study that for awhile before taking the test. Understand how English sentences are constructed (i.e. Subject-Verb-Object). Fooling around with this construction will help you on the DLAB.
Be able to recognize accentuation and stress patterns in words. Know where syllable breaks are in words. 
Have some experience with a foreign language. If you want to be a Russian linguist, it is not necessary that you have experience with Russian. However, if you have some experience with a foreign language, it will help you to understand that different languages use sentence structures differently than English.
Be prepared to interpret instructions based on pictures. For example, a picture of a red car is presented with the word "ZEEZOOM". Next, a picture of a blue car is presented with the word "KEEZOOM". Next, a picture of a red bus is presented with the word "ZEEBOOM". You must be able to give the foreign word for a "blue bus".
You should also know that on the audio portion of the exam there is no repetition of the questions. Once an item is given there is a brief pause for you to answer and then the next question. Be prepared for this; if you think you can think your way into an answer on any given question you will miss the beginning of the next. This effect can snowball and probably leads to some people with good chances going south due to nerves. Listen carefully and go with your gut. Be ready for the next question.

Qualifying Scores
The DLAB consists of 126 multiple choice questions. Applicable service policies require that each candidate for attendance at the Defense Language Institute be a high school graduate. For admission to a Basic Language Program, the following minimum DLAB scores are required:
85 for a Category I language (Dutch, French, Italian, Portuguese, and Spanish) 
90 for a Category II language (German) 
95 for a Category III language (Belorussian, Czech, Greek, Hebrew, Persian, Polish, Russian, Serbian/Croatian, Slovak, Tagalog [Filipino], Thai, Turkish, Ukrainian, and Vietnamese)
100 for a Category IV language (Arabic, Chinese, Japanese, and Korean) 
Individual services or agencies may demand higher qualifying scores, at their discretion. For example, the Air Force requires a minimum score of 95 on the DLAB for all Cat I-III languages, and 100 for Cat IV languages. The Marine Corps requires a minimum score of 100 for all languages, although they will waiver it to a 90 for Cat I and II languages. The highest possible score on the DLAB is 176.

Re-Tests
Individuals who fail to achieve a qualifying score on the DLAB can apply to re-test after six months. Requests for re-tests by individuals who have already made a minimum qualifying score are approved only based on documented military necessity, and must be approved by the appropriate commander (ie, recruiting squadron commander).