I do subcutaneous shots with 23g needles meant for IM. It's easy. Here's my entire process:
1. Warm vial by holding it in the bend of my knee for approximately one minute (makes drawing up much easier/faster)
2. Clean top of vial with alcohol swab
3. Open packaging on syringe and uncap, draw up an amount of air equal to dose
4. Inject air into vial (to maintain internal pressure)
5. Hold vial upside-down while drawing the oil - I pull back more than the dose, then use that excess to push the air bubble that always forms back into the vial - triple check that the dose is correct/all excess is back in vial, remove needle from vial
6. Pinch up an injection site (I use abdominal fat), release the pinch but keep fingers on either side of the site. Clean with new alcohol swab, let dry. Pinch the fat back up
7. Insert needle (I just don't put the entire needle in to compensate for the extra length), let go of fat, inject
8. Keep needle in for 10-15 seconds, maintaining pressure on plunger, withdraw, and immediately apply a clean bit of tissue to the area to check for leak or blood (there is often a very small oil leak, it makes no difference)