Minimize Machines.

If you're interested in resistance training (and you should be, since it's one of the most effective ways to increase strength and build metabolism-boosting muscle), you want to make sure that most of the exercises you do use free weights, like barbells and dumbbells, instead of machines.

Free weights allow us to move our bodies in the most natural patterns, as opposed to machines which operate on fixed patterns. What this means is that if you have a bad shoulder or a bad knee, for example, free weights allow you to push or pull the weights where you'll feel no discomfort, while a machine tells you "Nope, this is the way your body's going to move." This fixed pattern of movement is responsible for more training-related injuries than anything else.

In terms of exercising at home, you can perform every basic exercise needed to train your entire body with just one barbell (or even just one dumbbell).  You'd need at least 5 separate machines, or one large-sized "home gym" unit to do the same job.

So, a general rule of thumb: For every three free weight exercises in your workout, perform no more than one machine exercise, if any at all. Any more than that, and you're most likely taking the long road to your goals. Free weights are definitely the fast track.