The first and most important thing to do to improve your driving skills and prepare for your driving test is to practice! If you are not comfortable behind the wheel then you will be much more likely to make a mistake.
You also want to practice smoothing out your movements. While this can be hard to do when you are first learning, it should be something you get down before you go for your test. This means that you don’t want to slam on the brakes every time you stop or push the accelerator almost to the floor when you go.
Smooth driving also means that you should keep any movement on the part of the steering wheel as smooth as possible. Even when you turn, it should not feel too jerky and changing lanes should barely be noticeable.
Other things that you should practice is following at the proper distance and never getting closer than three seconds behind the vehicle in front of you. Stay in the correct turning lane and know where you are supposed to stop at behind a stop sign.
Most of the time when you are first learning most of your attention is focused on driving the right speed, staying in your own lane, and other vital things that are right in front of you. However, as you grow more comfortable with these you should make yourself look into your mirrors more often to see what is around you.