Google "subcutaneous injection" images. You will get many good pictorial explanations. A pinch of the skin on the midsection is probably the easiest. If you have pain or bruising your are probably hitting muscle.
I suggest 2 injections per day to avoid sides. From what I read, though, it is important not to exceed 0.025 mg/kg/day. This is found in several studies like http://www.ncbi.nlm.nih.gov/pubmed/8637402. You will still get results if you go slow and will probably have less freckling or spots.
Switching to a maintenance dose was a good decision because I am now very tan and do not really want to get much darker. I will continue on the maintenance does through the summer.
Thanks to Chris and the rest of the folks on the site for your help. You really made it easy. ;D
Here's a brief update. I have stuck with a maintenance dose of about .4/mg every 2-3 days. I continue to get darker even with just casual sun exposure. I now have a dark tan and total protection. I am going to stick with the maintenance dose and see what happens. I expect I will get very dark this summer. I have no sides at all that I notice. My brown spots have not changed in weeks.