Everyone worries about taking a test no matter what it is for. Whether it is a physics class or a driving test, it still causes you to worry. So here are some tips that I use to help my self remain relaxed and laid back.
Plan everything ahead of time. You should always know when your test is going to be and mark that date on your calender. You should also make sure you know where to be and how you are going to get there.
Once you are sure when and where your test is you should study and prepare. The key here is to not study too much. If you study too much you start thinking about it too much and thats when the nerves really start to become overwhelming. Make sure to spread out your study time as well so that you aren't doing everything all at once.
Once you study all the material at least once then its time to just forget about the test. Maybe the day before the test or whenever you feel like there is no more to study then just stop thinking about taking the test, pretend like you don't have to take the test. You can sit around and just watch TV or go hang out with your friends
Make sure to go to sleep early, try to get 6 or 8 hours in. Don't forget to set your alarm to and wake up early enough so that you won't be late and you have at least 10 or 15 minutes before the test to just sit there. Going to the bathroom is a good idea too, you don't want to have to worry about anything else while you are in the test.
Before the test its good to just not think about it again, maybe plan on what you are going to be doing after the test. There is no sense in getting all worked up right before the test like so many people do.