I can't donate plasma because large gauge needles scare the hell out of me. The tiny ones used to give a flu shot or allergy shot into muscle are OK, but I will pass out if you try to shove a needle the size of a pipeline into a vein (which seem to be hard to find on me).
The last time I gave a blood sample was 7 years ago and I got some novice poking around to find a vein as I laid down (sitting is not an option unless I want to risk hitting the floor when I pass out). The novice had to call in somebody who actually knew what she was doing to find a vein and my vision had gone almost black and I was soaked in a cold sweat by the time the needle was out. A couple more seconds and I would have passed out. I looked so bad they wanted me to stay down, fearing I'd fall over if I sat up and the doc handed me a huge pile of paper towels to dry off with as it looked like I'd just gotten out of a sauna.
I'm not the kind of guy you should have the novice blood-taker play with. I need the expert who can do it ASAP.