I am also one of those who had trouble with the presta valve at the beginning of riding a road bike. I bent the valves two mornings in a row on a long ride and out came the air! SOOO frustrating! One of the things I have learned is that once I have the proper pressure in the tire, (I put the valve at knee level to pump) I use both my thumbs and "pop" the pump off the tire. I found that if I just used one hand to pull the pump off that I was more prone to bending the valve stem. I also was more prone to pulling the valve stem out of the tube, resulting in an instant flat.

So stand behind the wheel after you have the pressure at the level you want. Wrap your fingers around the tire and use both thumbs to push the pump off the valve. Try it!! I learned this trick from one of the women on a cycling trip I took and I have not had a bent valve stem since then! Hope it works for you, too.