Certainly, this website has many articles on it, but my best advice, which I generally apply to almost any topic you wish to learn more about; get books!
"The Projection of the Astral Body" by Sylvan Muldoon and Harewood Carrington. This is generally one of the best books I've read on it; only really the last few chapters put forth the practice, but the theory, concepts and potential explanations within all other chapters can really help to give you an idea of "what it's all about".
There's also Robert Bruce's "Astral Dynamics", which is generally hailed as being one of the best books currently in-print on the subject matter.
There's also a bunch more, like "Navigating the Out-of-Body Experience" by Graham Nicholls, "Astral Projection and Sceptical Occultism" by Nick Dutch, and of course, the trilogy of books on the matter written by Robert Monroe. These are the kind of books that turn you from being somebody who thinks about AP and hopes to do it, to somebody who can actually do it, at some point.
There are probably plenty of websites online that put forth practices, but I still think that getting a good base for the theory and ideas behind it is important too, and, much like with Lucid Dreaming, the more you study and think about it as you learn more along with it, the more likely it might be to happen.
Have fun. :-)