Kelly Swa has recently Started his own ABS - Revit Systems Blog. Check it out here.
Bucking the Systems
Now, the really cool thing is that Kelly is teaching an online AUGI class on parametric parts this August. I highly suggest you sign up for this one, because I can't think of something more complex to learn on your own.
The same link below will allow you to sign up for my class in September on creating block-based parts. It will be a spin of what I taught at AU last year with a lot more detail and different parts added.
AUGI Training Program (ATP)
It's all free thanks to the fine folks at AUGI. If you are not a member this should be more than reason enough to join up.
Good luck, and I hope to see you in class.