There is no real guide to this that i know of but there is a trick to it. When you find a beach ball simply a walk through it fast to shoot it up into the air, after that you will see the shadow of the ball on where it will land simply make sure Tommy is standing on the shadow so that the ball lands on his head. ( When i did this i barely had to move Tommy maybe just tap the analog over a bit) Once it reaches five the trophy should unlock