I have been using Beta for over five years now. I totally agree with the suggestions to rotate the sites - I always used to 'hit' my thigh, but I ended up getting some pretty obvious 'hail damage' there.
I found that if I inject an area too frequently, the shot is more painful - I think the skin must thicken. The upper, outside of the front of the thigh (god, did that make sense????) was the least painful area for me - the lower I went toward my knee the more it hurt.
I use the upper part of my butt a lot (plenty of surface area there - and subcutaneous fat

) it is possible to do this to yourself, instead of pinching I sit on a hard chair and press down on the skin above it so that it is firm.
Do invest in an autoinjector - they are much better and I am WAY too much of a chicken to do it any other way.
Cheers
Lyn