To grow in the gym, you have to lift big. Lifting big means going as heavy as you can with strict, form.
Mix Things Up
The body resists change. It prefers regimentation. To grow muscles, you need to keep your body guessing. You don't want your muscles to adapt to any exercise or routine. So mix up your routines and exercises from time to time.
Stick To The Basics
Too many lifters add too many different exercises for each body part. To get the most out of training, work your routine around basic compound movements like the squat, bench press, military press, barbell rows, and the like.
Warming up isn't for pussies. It helps prevent injuries. It keeps you out of bed and in the gym.
Minimize Sets, Maximize Intensity
Some hardcore lifters do 40 sets for legs or 20 sets for arms and grow. For most of us, this is not good. Find out what works best for you.
While machines can be good for isolating muscles, free weights involve ancillary muscles and are therefore better for putting on maximum size.
For maximum muscle, keep reps in the 6-10 rep range.
What do you want, an impressive physique or to struggle lifting an impressive weight? Strict form is key.
Focus on working larger muscle groups before working smaller one.
Eat Right, Eat Often