How to prepare for the written exam. If you're not a good test taker get some help. Get a tutor, get an account with one of the online testing sites and practice. If you know that you have a weak spot, such as math, get help in that area as well. Take lots of tests. This means applying to a lot of departments. Maybe even some where you don't want to work. The written exam I took when I got hired was the exact same test that I had taken 3 previous time in the 6 preceding weeks. When I saw that it was the same test not only did I know exactly what to expect but I remembered most of the answers. It allowed me to take the test and then go over it a second time.
Things to remember on the day of the test. Be early and bring a couple of #2 pencils. I've never taken an exam where the department didn't have some extras but it would suck if that happened to you. Leave your cell phone in your car. One last thing on the written exam. Watch your time. Skip the answers you don't know and come back to them. Don't forget. If you do run out of time, guess. You miss 100% of those questions you fail to answer.
Next, Researching your department.
Previously, Whose Hiring