I check both arms, even if the person tells me which they think is their best,  as I have found i can often feel a vein anyway.

 

and often with difficult veins, I will have the tourniquet on and I could feel the vein and then I cannot feel the vein,   I back off then, remove the tourniqet, leave a few minutes  and apply again and feel again.

 

I do not insert the needle until I am happy I can feel that vein

yes, you have a fasting glucose, drink the solution and the repeat glucose levels are done to see how quickly your body processes the glucose and how your body responds over time

I wasn't aware that some people had that much trouble when they need to have blood tests done.  I am one of the lucky one who has no trouble, but now I understand when I go for a blood test the lady calls me her favourite client.