I have been building large upper-body muscles with resistance body weight training on the pool. That means pushups essentially, but the steps-area of the pool let me do them with full hanging body weight and with many wide arm spreads.

It's important to have variations in how to position the pushups. I do 30-70 reps depending on difficulty of arm position, usually two or three sets a day max, each set can be a different position. When I feel strong I do reps slowly both on ascent and descent. Due to my flexibiility (a very important factor in having elongated shape big muscles in pecs etc), I also do triceps also in many widths by putting my hands behind me at the pool border and lifting my weight; it is very demanding exercise, also works back and shoulders.

However the most important tip no one realizes for growing muscle, for having resistance, for having tonus and for a real fast recovery comes from India. Apply oil to body (preferrably all of body, leave for 40+ minutes as you sit or meditate, listen to music; use old clothing and wash it separately, oil trashes and stains all, and it quickly ruins any stretch fiber and elastics bands on shorts etc). Coconut oil gives the most mass, good for hot season. Ginger oil good for winter, get south american Buriti oil if you can (mix some drops to coconut, use with utmost caution, observe the effects, how it makes you agitated etc, never use it in summer), brazilian indians used it for going to war, it makes muscles really bulge, The greek used oil for wrestling matches too, and for looking strong. Oil is not all about the shiny effect, it improves muscles tremendously.

I would compare the effect of not applying oil to the muscle parts after a workout to not eating any protein after a workout. It's such a dramatic effect.