Knowing the test format can be helpful for studying purposes. For example, if you know that the test will be in essay format, practice organizing your thoughts in English and review written grammar rules. For oral tests, practice pronunciation, syntax and correct spoken grammar with a native speaker to ensure your answers will not only be correct, but also sound fluent and thoughtful. If the test requires an answer be given in 15 seconds, practice thinking on your feet in identical conditions.
Even native English speakers make grammatical and syntactical errors. Unless the test is specifically measuring accuracy, focus on meaningful communication, not on the size of your vocabulary or your perfect grasp of passive voice. Memorizing every grammar rule won't help you when the test requires you to describe your summer vacation or ideal job. Listen to the way native speakers communicate and try to model your own speech after theirs. You need to be comfortable with "real" spoken English to be successful.
Don't panic if you see or hear a word you don't understand. Instead, watch out for keywords that can help explain its meaning. Train yourself to discard unknown words and focus on those you do know. For example, if you're reading a passage about a doctor visit, ignore words such as "stethoscope" or "pediatrician." Other words, such as "parent," "child" and "cold" can help you discern the passage's overall meaning. For oral tests, in which total understanding is often necessary for producing a correct answer, ask the proctor for a synonym of the word you don't understand.
Train yourself to be comfortable with silence between questions and answers. Consider oral questions for a moment or two, gather your thoughts and speak when you are ready. Ask questions for clarification. For essay tests, make a rough outline before starting to write. For other test formats, such as multiple choice or true/false, check that you understand the meaning of the entire question before answering. For example, "The girl went to the store" and "The girl almost went to the store" mean two completely different things. Read slowly and consider all possibilities before giving a final answer.