Put on a mental seatbelt and read this:
The Frank Kepple Resource
It is long but well worth the read. It doesn't focus as much on techniques as it does the nature of reality. Frank describes consciousness as having four focuses, in which our physical realm is only the first focus. He says that when we astral project, we are not really leaving our bodies, we are simply switching our focus or awareness.
Some parts of this are emotional, and after I read it I found myself wanting to do retrieval work.
Here I am assigning myself tasks and I haven't even projected yet!
Anyway, a lot of this resonated with me. I hope you find it an interesting read, too.