next time you have surgery tell you get nausea when going under, I had that happen to me and now I tell them every time and they give me additional medicine to prevent that. The cheat spot they use on me is on my wrist under my thumb. That one hurts but not as bad as getting priked a ton. Also make sure youre hydrated and the draw spot has been warmed up.
I have to tell the nurses to take from top of hand, not ideal but lst time pro surgery took multiple attempts at usually spots was bruised like crazy, had to get head nurse to do the top of my hand
I have trouble too with blood draws and IV's. One thing they did last time was inject the area with lidocaine. This helped because they did a sensitive area. Another thing is to have heat packs placed on the areas they want to try. They should have these available. This will plump up the veins. Hopefully you will get a better team his time. It usually takes 3 times for me. My record is 13 times. I hope it goes well. I guess if you can get very hydrated the day before if you have to be fasting the next day. If you aren't fasting then drink a lot of water before you go.