I warn the lab people, and they always seem to want to try first. I think it is a pride ting to stick a hard stick. Damn them their pride!
I am the same, crappy veins that just roll away in fear of that needle. I have two good places only. I tell the techs and show them.. "here or here" only. The blood flow often stops and I have been told before that it was my fault because I crossed my legs!