Drawing blood

I transferred from a telemetry floor to an adolescent psych floor. On the telemetry floor, we frequently had to start IVs and draw blood. I sucked at both. Even though I would go through all the steps correctly...tourniquet tight enough, arm held low, etc. etc. I would always either never see the blood return or I would see it and then it's gone or the vein blows. I've always felt so horrible about it because most of the other nurses never had a problem with drawing blood or starting IVs, even when they did, it wasn't often. Now on the psych floor, I don't have to deal with IVs anymore (thank God!!) But, I still have to draw blood. I thought it would be super easy on kids because most of them have excellent veins. Then, I had to draw blood from one strong teenager with very good veins that popped out so good that you could see them from across the room, and when I went to draw his blood, I didn't see any blood return at all in the needle. I told a senior nurse that I tried, but, it seemed as if his veins kept rolling. She stuck that needle in his arm and drew the blood in like 2 seconds it seemed like. I felt terrible. I was wondering if they were talking about me behind my back saying, "She came from a medical floor and she can't even draw blood." Can any of you senior nurses give me some good advice or tips on drawing blood? Thank you.