FeeFighter's ebook and many of their blog posts are a pretty great resource. Another great resource (especially for Rubyists) is Amy Hoy and Thomas Fuchs' http://jumpstartcc.com/
If you don't want to bother worrying about the details of setting it all up, look into Stripe.com or Samurai from Feefighters
If you don't want to bother worrying about the details of setting it all up, look into Stripe.com or Samurai from Feefighters