you suppose to keep on adding heavy weights as you move up with each set and lower the number of reps due to the weight being heavy. Like 12,8,6,4,2 for example, works for me. also take over one min of resting time between sets. i personally do bench press, incline bench press, chest machine of 3 really heavy sets of 4 to 2 reps and then move on with triceps exercises. Remember the more heavy weight you push out the stronger you will become.