First off you need to be aiming to progressively add more weight to the bar at each workout and focus on doing exercise that several muscle groups at the same time such as the good old bench press which targets the chest, arms and shoulders. Since you are lifting heavy weights you only need to focus on doing 3 to 4 sets of 5 to 6 reps per exercise.
Always make sure you have a rest day between each heavy workout session so your muscles have time to repair that important muscle tissue. Giving your body rest also gives it more time to build more strength by adding muscle to prepare itself for the next time you workout.
This is the main reason y