Make sure to get plenty of sleep, dont cram the night before the test. This will affect your thinking ability while taking the test.
Have several review sessions the week preceding the test, to make sure you've properly covered the material.
Have a good breakfast, I like toast with jam and oatmeal, sugary cereal can make your attention span low and affect how much effort you put into the test.
Take notes! Writing something down has often helped me memorize it better, and led to better performance on the test.\
