With the exception of tapping on the glass I think you're off to a good start. If he's already out and about, then no need to alert him that you're coming, but otherwise, a gentle wiggle of the hide he's in will alert him. Th3n just slowly lift his hide and present yourself. A gentle stroke to show you aren't a predator is a good idea. Like you sid, picking him up from behind is also best. If for some reason he seems like he may be in strike mode, whether defensive or food driven, a little tap or two with a paper towel tube usually calms them down.
I know it's hard at first but try to put any fears behind you and pick the animal up with confidence. They are good at reading us, if we are calm, they will also be calm.
Keep handling sessions short to start nd just watch your snake, learn his movements and mannerisms.
You're off to a great start, keep up the good work.