The VG is supposed to be the safest spot, I however have never been able to convince myself to pin there because it just doesn't feel like a injection site to me, it feels too solid like I'm gonna stick the needle into a rock.
I did my entire first cycle in the upper outer quarter of the glute, there's a lot of room for error back there. I did my first cycle with 21g 1.5in Needle no prob back there. Over the years I switched to a 25g 1in for glutes and even use a slin pin sometimes when I'm lean. Deeper is better but if I ended up sub q it still works, it just leaves a little bump for a day or two.
Delts, much easier to reach, 25g 1in works great there. I just flex the delt and find the center of the meatest part. Look up delt injection site it's easy to find. If you get below 12% bf that's another site you can hit with a 1/2 in needle if need be but 1in probably better. Delts will be very sore post injection for a few days but over time you will get used to it. I find it benificial to line up my delt pins with shoulder day so that I can get some blood moving in there. But after a while it'll be completely pain free.
Finally, my absolutely favorite spot is chest. It took a lot of courage to pin there but since I did I have not had a single pin go wrong. 28g 1/2in and burry it in there. I've found 6 spots that are super easy, there directly in front of you and pip is minimal. After you get past your initial spot I wod say try delts and after delts maybe try chest. The more locations you have the better.
For chest those two highest dots are the easiest then the next two are pretty easy and the lowest two I'm only comfortable doing when i'm really lean so I can see where the veins are
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For side delt if you look at my tattoo, that eyeball in the middle of the sun is about the area for the delt injection