To gain muscles and nothing else? Well, working out isn't going to make you gain fat, if that's what you are worried about. Any work out will help you tone and build muscle. To bulk up a bit faster, you weights or resistance bands. A good rule of thumb is to do 8-10 reps per set. It is believe that this will add bulk, rather than tone. If you want to tone and sculpt a muscle, do 12 reps.