If you intend to go from a PPL to ATPL the first thing to do is get your class 1 medical. It would be an awful lot of money spent if for some medical reason you are unable to qualify for a class 1.
Get hooked up with a really good instructor, the more experienced the better!
As P40Warhawk recommends watch Aircraft investigation, as it does help you understand how an aircraft works, it's limitations and solving problems when things go wrong. Saying that, it may put you off or make you very nervous especially as a new student pilot
Glendalegoon suggests learning in a piper and not a Cessna without giving any reason ?? Personally I would choose the Cessna over the Piper, so would suggest you read up on the pros and cons of each.
King Air used to do these DVD's and they really are quite good, anything visual is always better than reading words out of books
Prepare right from the start for your first lesson. Phone the school talk to your instructor and ask him what you will be doing for on your first lesson and go study up, make ready theoretically so you are prepared. Always make sure you are prepared for each lesson before the lesson, so if your instructor has forgotten to say what you will be doing on your next lesson ASK!!
Finally Enjoy!!