A full body workout is by far the best way to get in shape. However, there are certain things that you should know beforehand in order to make your workouts more effective. The first thing that you should keep in mind is that you want to limit your exercises to just one for every muscle group. You are going to be working out your entire body, so you have to keep it short.
Also, you should vary your exercises for the different muscles groups with each workout session. You do not want your muscles to get used to doing the same thing all of the time or you will stop seeing results.
You should also keep your workouts limited to just a few sets for every muscle group. This is because when you are doing a full body workout, your focus should be more on intensity rather than the amount of exercises you are doing. If you do it this way, you will actually start being able to lift more weight.
Forget about using the machines. You will be much better off using free weights, as the machines just isolate everything. You can use a leg press machine in combination with the free weights, but in most cases you will be better off just staying away from the machines.
When you are doing this kind of a workout, you should only be in the gym 2 3 times a week. When you work out your muscles actually get broken down, and it is the repair process that allows them to grow. You need to allow sufficient repair time for your muscles in order for them to reach their maximum growth potential. This is one of the benefits of doing this kind of workout. You get to exercise all of your muscle groups without having to be in the gym every day, so your muscles can get the repair time that they need. Plus, you can take the weekends off if you want! Keep in mind that you are going to be better off if you start out by using less weight. You can get rid of excess body fat by doing more reps with less weight.
It almost sounds too obvious, but be sure to eat. Working out like this is going to burn up a lot of your energy. Plus, when you do high intensity workouts you are going to be increasing your metabolism. This means that even when you are resting you will be burning calories and fat. What you eat depends upon your goals and whether you are in it for fat loss or muscle building.
Try not to waste time, and keep your periods of rest between sets as short as you can. You are going to be trying to work out your whole body in a short period of time, so you have to keep it going.
Finally, when you are doing a full body workout it is going to be important that you track your progress by logging your workouts in a journal, as this is the key to reaching your fitness goals!