I get transfusions every 6/7 weeks. The nurses at the Monterey Hospital, CA, first put warm, wet pads on my arm before inserting the needle. They told me the warmth expands the veins and it makes it easier and less painful.
Now they do it on the vein a little above my wrist. Hard to explain but is the vein that ends in the thumb. It did not hurt at all.
The first time they used the vein on my hand and it was painful. One doctor told me that was because there are lots of nerves on the hand, and if they get close to one of them then it hurts. But, even then, the pain is not bad, just unconfortable. So, now I told them my hands are off limits.
You can also ask for a more experience nurse if your Dad has veins that are difficult to find. Experience makes a big difference. I requested that and they did not mind it at all.
I hope the next one goes well.
Kitty