Offset chest and shoulder presses with a few sets of pulling exercises, such as pull-ups, pull-downs, and rows. Balancing your exercises in this way will help to work out the muscles that are neglected during the presses, which will in turn lead you to bulk up faster and increase your strength.
If you are unsure of what exercises to do more often, throw in more dips, push-ups and chin ups. These exercises have stood the test of time in their proven ability to build upper-body mass. Nor are they likely to be replaced by other possibilities in the near future.
It is a good idea to work out in the presence of others in order for you to push yourself to your limit. Many people slack off a bit when they are lifting weights if they know that no one is there to notice that they are not working as hard as they could be.