As a recent adopter of Astro Photography Tool, I can agree with Shane's comments, it's a very good tool that has a bunch of very useful advanced features. Although, as you start off into program controlled capture it can be kept very simple and you can just integrate new processes as you become comfortable with each of the features. Just using it as your DSLR capture program can improve your efficiency during a session, and when the same program can also take care of focusing, plate solving, dithering and the like, it becomes a very powerful piece of software. As Sil mentioned, the development of a workflow shouldn't be overlooked, things can get complicated quickly when you start to add new routines.
Jim Solomon's AP cookbook is getting a bit dated now, but this was my bible many years ago with respect to a good capture routine.
I'm going down a development path for a simple 1100D and an 80mm scope that started with basic camera control, and now adding functions as they become necessary or useful.
APT DSLR control
EQMOD (Umbrella PC mount control solution, hand controller delete)
Guiding solution
Planetarium program
EQMOD/Planetarium mount control (click and point control of mount)
APT Plate solving (good for framing and fine syncing of the mount)
APT Auto focusing
Not looking too closely at the processing side yet, not until producing good consistent data becomes the norm.
G