Once you've built a strong base of strength (that should always come first in the gym) add some size-focused rep ranges and specialized hypertrophy exercises.

Reps for Size

To maximize muscle growth you need to leverage classic bodybuilding rep schemes. The sweet spot for reps is 8-12. That's heavy enough to create significant tension in the muscle, yet light enough to allow multiple reps and metabolic stress – another key component of muscle growth.

Another effective strategy is high-rep sets of 12-20 or more reps. Though this has been called a "muscular endurance" rep range, these high-rep sets can create one hell of a muscle-building challenge, especially with isolation exercises and challenge-based finishers.

Techniques for Size

These are isolation exercises, but now that you've built your strength base you can perform them with weights not covered in pink vinyl.

Pre-set holds

Just pause at the hardest point, or mid-rep, and hold the weight there for 15-30 seconds. This works great with a barbell curl. If you find yourself struggling to hold the weight for this long at the beginning of the exercise, decrease the weight. After holding, go immediately into 8-12 reps without resting. Pre-set holds will improve your mind-muscle connection and accelerate muscle growth.

Failure training

This is a great way to get a good pump and build muscle on the heels of your strength training. In fact, one recent study found that when you perform an exercise to failure with loads of 30% of your 1 rep max (very light, 20+ reps) it's nearly as effective as using loads of 80% of your 1 rep max. So when you train isolated muscle groups, do the exercise until you can't do it any longer. You'll get the pump of your life.