First, you want to get the basics down. This is easy. Thinking Like a Computer Scientist in Python is a useful book for non-programmers, while the online tutorial is a useful tutorial for programmers needing to pick up a new language. Then read, once-through and without bothering yourself about details, the library reference. This will make sure that when you need something, you’ll have a vague memory of “I saw it in the reference”, and look it up. This will be useful later, because it will stop you from re-inventing the wheel.
Next, choose some open-source programming project in Python, preferably one that is well-managed and documented, and try to fix some bugs. In parallel, start your own Python project. You’ll suck at first, and you’ll progressively get better at it. After a couple of months, you’ll feel comfortable with Python. After six months, you’ll realize you now know Python much better. A year, and you’ll feel you are now finally decent in Python. After one more year, you’ll see how you now *truly* understand Python. By this time, you’ll understand that it’s a life-long quest, but one with many rewards along the path. This is enlightment.
Note: observe how none of the advice involving buying a book. I never found myself helped by any Python book.