Some websites to start with:

An astronomical images processing software: IRIS by Christian Buil. Free, it’s in French and English. This software requires some learning. It is very complete, effective and well documented. You will find a complete documentation and the list of commands, as well as the lessons that complement the documentation and the links.
Two free programs are available for planetary pictures processing: Autostakkert!, video processing, alignment and addition; Registax for cosmetics. 
The Pierro Astro website is much more than just a commercial page. The munts are adjusted, tested and supplied with the complete summary of the device. Moreover, they have always answered my technical questions and doubts. Its advice on choosing the right material has been very valuable.
If you wish to replace the IR filter of your digital camera by an ASTRODON filter, you can surely get good advice from Richard Galli
Light pollution maps for astrophotography
Webastro is an indispensable website: it includes everything related to astronomy, news, information, etc. Their forums are fantastic to share photographs, technical advice, tricks and a gallery to store your photos. The conviviality that you can found on this website allows you to gain experience, both for the beginner and for the initiated fans.
Another perfect website for fans of astronomy is Astrosurf. We can comparable it, in certain aspects, and in others it is complementary to Webastro. They also edit an excellent magazine "Astrosurf ".
Planetarium it’s a program, indispensable and free. I have incorporated the photographed landscape of my fixed installation. This allows me to visualize with precision the moments in which the objects that I want to photograph will be hidden by obstacles (the house, the trees). It is very useful before starting a photo session.
Before installing all the equipment, it’s worth checking the real-time satellite tracking
A virtual moon atlas composed of pictures from different space probes. Can provide high-resolution pictures. It’s marvelous and for free!
The Jupiter2 program gives you the position of the satellites and the big red spot. It’s free. 
Siril, an other astronomical images processing software. Recently developed and faster, it can be a substitute for Iris. Free, it’s in French and English.  For Linus and Wondows