Get plenty of sleep. Your brain won't function properly if you are tired, so try and avoid an all night drinking fest the night before.
Make sure that you use everything that is available to use during test. Generally you will be given a pen and paper but no calculator for the test. If you will be able to answer the question quickly with the aid of pen and paper, by all means use it.
Don't take too long on a single question. The Wonderlic test is usually timed. In my experience, I had twelve minutes to answer 50 questions. This means that if you don't know a question, then don't sit there and think about it. Most likely, you are just going to guess wrong and cost yourself some time. It is imperative to prioritize and only work on the questions that you can get correct.
It is said that you can't prepare for an I.Q. Test. I believe this to be false. Make sure you check online resources for sample test. You probably won't run into any identical questions when you take the test, but you may find similar ones. Practicing will also get you used to the time limit and back in the test taking mode if you have been out of school for long.