How to start Indie game development

I am a game Programmer who has developed serveral online games, I have used Torque engine for two years, and are familiar with Garagegames's products.Recently ,my friends and I are interested in Indie game development, we want to make our own game .We have many questions about Indie games.Could you please give us some suggestions?
What shall we do at the begining? How many downloads count for a game on the average.
Thanks a lot.