I strongly suggest that even if your state does not require a pre test, it is a good idea that you enroll or participate in some form of GED training.
Many community agencies offers free or reduced rates for GED preparation classes and will then pay for your exam, upon completion of the course.
If there is no way you can complete or participate, in person, don't give up, you can also sign up for an on line class.
Another way to prepare yourself is to buy GED study books and study guides.
The GED is made up of five sections and it's possible to pass one or more sections or fail one or more sections. The sections you fail or score low in, would be the area(s) you would want to devote most of your time study time to.
Above all, remember no one knows the exact questions that will appear on the GED exam, so never buy into a scam where you are told that you can be guaranteed the answers to questions on the exam.