The number of push-ups you should do a day depends on the result of your push-up fitness test. First, do the highest number of push-ups you can in 2 minutes. Determine the repetition count per set by dividing the number of push-ups done by three; do three sets per day.
For example, if you did 12 push-ups during the fitness test, you can do four push-ups in three sets, determined by 12 divided by three. Rest for 30 seconds in between sets. Push-up workouts can be done every other day. Two to three repetitions can be added to each set as you progress with the workout. Do the push-up fitness test again after four weeks to recalibrate.