This preparation drill for the bench press is a superset of the dumbbell squeeze press and flyes. Prior to bench pressing you need to activate the pecs (making them more responsive to the neural drive), and do loaded stretching to avoid pulls and tears. Static stretching will have no benefit to your bench press performance and might even decrease it.
Something to remember: Because of "geared" powerlifters (using a bench press shirt) one common belief is that the bench press is mostly a triceps exercise and the pecs play a limited role. But this doesn't apply to those of us who bench without wearing a supportive shirt (which basically does most of the work in the range of motion where the pecs are most used).
If your pecs are strong and activated, the CNS will rely more on that muscle to do the job, and the delts won't be loaded up as much. This reduces the chances of a shoulder injury. The pecs are a much stronger muscle than the delts, so becoming better at using the pecs when bench pressing will lead to bigger numbers.
For the squeeze press, press two dumbbells against each other. As you press up, squeeze them together. When using this exercise to build muscle, squeeze in as hard as possible and go up slowly. But when using it as an activation exercise, use only about a 75 percent of your effort when squeezing in and go up at a controlled, but not slow, speed. The goal is to wake up the pecs, not burn them out.
Do 8-12 reps then immediately move to the dumbbell flyes on which you gradually try to use a greater range of motion to stretch the pecs. Do 8-12 reps with these.