First The endo will put you on either Androgel or the test patch, if the endo asks which you prefer " injection, gel or patch" get the injection.
Second if you do get the gel or patch, usually the starting dose is 5mg a day then you will be tested again in three or four months...and so forth until they dial you in.
In my case they had me up to 7 grams a day and my levels didn't go past 175, so i was put on the injection. By the way if you want the injection tell them the patch is giving you a severe rash, if the give you the gel tell the same thing. In my case neither the patch nor gel worked.
Third if and when you do get the injection it will be dosed at 200mg/ml twice a month, ask the doc if you can self inject and then do 100mg/ml a week, then tell the doc you were in an emotional roller coaster and decided to do it weekly at 100mg/ml, usually the doc will agree and officially put you on a weekly injection schedule.
From here on out the process starts all over again, getting bloods every 12 to 16 weeks checking your levels and adjusting your dose. Im on 150mg/ml a week and im loving it. However i know i still need a little more.
Oh yeah before i forget make sure you tell em if your getting morning wood or
LACK OF morning wood. This will help them to dose you properly

.
Last they will not prescribe HCG or an AI, you can try and ask maybe you'll get lucky but i haven't been.
Hopefully this helps you out, from one vet to another.