nikk,
Get yourself semi-erect and use an overhand grip, palm facing down.
Use an ok sign grip near the base of your cock. Slide (if using vaseline) about an inch or pull (if doing it dry) and then squeeze the bejeezus out of your cock using the other 3 fingers while maintaining a firm ok grip.
So, if you were to show the okay sign to someone you would have 3 fingers in the air...FU, ring and pinkie fingers...these are the ones you squeeze with.
You will need to experiment for the proper feel but you'll get it. The really nice thing about them is that you can do them anywhere at anytime as long as you are in a bathroom and can have a couple of minutes for a few quick squeezes.