Patience - huge pecs take years to develop.
Don't neglect squeezing exercises; alternate pushing and squeezing exercises (like flys)
No shoulders/triceps in the 2 days prior to chest workout
Don't overtrain; work your pecs every 5-7 days.
When you train chest, hit it hard. Don't mix it with exercises for other regions of your body.
Vary rest between sets weekly.
Use drop sets when going heavy, or you won't get enough of a workout.
Shoulder packing - Pull your shoulders back and down.
Good nutrition
Hydration
Mistakes to avoid: