The best thing you can do to pass each level is relax - very easy to say and almost impossible to do! Take slow deep breaths in the plane as you are climbing to altitude, and a very deep breath just before you jump, and SMILE! It generates a physiological response in the body which will help release some tension - it is much easier to arch when you are as physically relaxed as possible.
Go over the jump sequence in your head again and again and again (this will be covered fully in ground school - don't try to second-guess what they will teach you by asking on here, just be prepared to absorb the instructions). When you go over the sequence in your head, do the actions as well. You may want to tuck yourself into a corner for this because it will look a bit strange, but do it anyway! You want this to become as automatic as possible and the only way for that to happen is to practice as much as possible.
There is a thread elsewhere that talks about waiting until the day following ground school to do the first jump in order to let the instructions sink in. I was given the choice and couldn't decide but in the end the weather decided for me. I'm sure that helped because I had more time to practice the whole jump sequence and I could probably have done it in my sleep by the time I did get to jump, lol.
Each jump builds on the previous one, so it really is worth getting the sequence as fluid as possible.
And don't worry if you don't pass every level first time. It is a huge amount of information to take in, and requires a lot of coordination and management of the physical and physiological responses of your body, whilst overcoming sensory overload!