@anon84097: First, if your mate is not experiencing pain, you're probably doing it right.
Having said that, make sure you're using the thinnest needle possible. The B-D Company makes a 31 gauge needle that is about the thickness of a couple of hairs. They're great.
Next, make sure you're pinching up a fold of skin. Going straight in without pinching up the skin seems to cause more pain.
If you have pain with the first try, move the needle just a little way in either direction and try again, always pinching up some skin.
Ideally, your mate should be able to give himself the injections, but if this is not possible, you need to gauge what you're doing by his comfort level, not yours. Everyone is different.
I don't know how particularly trustworthy I am, except that I take Victoza once a day, SC, and before that was on Byetta twice a day, SC, and have been on it since summer 2008. Some days it stings, some days it doesn't. It never hurts for more than a second or two, and even then, it's not as bad as getting a mosquito bite.
You'll spring a "bleeder" once in a while, but don't worry. Just get the needle out and dab the spot with a little neosporin. No big deal.
Remember also, when you give the injection, to keep the needle in for a count of 15, to make sure the medicine is absorbed.
Most of all, let your mate tell you what's comfortable. If the medication can be given in the abdomen or upper thigh, for instance, allow him to choose the most comfortable site. I usually inject in my abdomen, but that's strictly personal preference.
One more thing: change sides, wherever you inject. Switch from left to right to center, up and down, so you're not hitting one spot too often.
Good luck and post back if you have more questions. I'll be around.