I love injecting quads. I find it the easiest place to pin. I sit down on the sofa with leg extended, dart it in to the outer upper thigh, aspirate, inject, massage. Easy.
I then go for a long(ish) walk to help move it around and the next morning 20/30 mins on the treadmill/elliptical machine.
It's the most painless and easiest area for me. I might have to try delts next...
Koi.