do them every other day. i stay between 25 and 35 reps per set, adn i do 3 sets. once you are more fit, you can do a lot more types. you can do diamond pushups, with your hands close, wide arm pushups, and various incline pushups. normally, keep your arms at about shoulder widthe apart. i would also do some crunches and pull ups if you can. that will give you the best all around workout