[gdl]

It depends on your goals and learning style. If you're just looking to be able to tinker a little bit with existing code, or learn best by doing, then jumping right in is probably the way to go. If you want a deeper understanding, and to avoid making as many beginner mistakes and poor decisions, books are a great way to pick up "best practices" without wasting time going through all of the worst practices first. But lots of people have found success with each approach so if one way fits your learning style better, by all means go with that one.

And really, the most effective route is to do both. Focusing too much on doing without the book knowledge results in creating terribly awkward solutions to problems that have been already been solved. On the other hand It's easy to follow along with a book and fool yourself into thinking that everything makes sense while lacking the experience needed to figure out how to put all the little pieces together to create something useful. As is usual in life, balance is key.