Here's what I do to get the weights up. Clean it off the floor and let it rest near the deltoids, like the starting position of the dumbell military press. Sit on the bench. Glance backwards towards the bench to aim for ur lying position, and with one swift motion, lie down and at the same time bring the dumbells to the side of the chest. This technique may seem complicated but its easy and prevents rotator cuffs straining. To recover, if you have strong ab muscles, go back to the sitting position. And if not extend to a dumbell flye position and drop the weights.
Works everytime.