And do not forget to try the exercises at the end of every chapter. They are the key to fully enjoy the book.

There is also the online tutor:

http://icampustutor.csail.mit.edu/6.001-public/

Thank you very much for sharing this. I will be using this to verify my solutions for the exercises. I am planning to work through the book slowly but thoroughly.

Watch the video lectures as well, they're well worth it - and since they're for an earlier version of the book, you don't get presented with exactly the same information as you would be if they were in sync with the current version of the book.

The exercises are actually scattered throughout the text. Definitely don't skip them, some of them are a lot harder and more mind-blowing than they look.