Since this will be my first post, I think it makes sense to get some basic information out of the way. Most of my posts will assume the reader has a basic understanding of python already. There are more than enough basic python tutorials out there so instead of re-inventing the wheel myself, I will reference a few excellent places to begin.
What is the best way to begin?
As a network engineer you may want to dive right in and begin writing some code to immediately use. I started out with the google copy/paste method of programming, and in retrospect I believe its best start from a basic programmer perspective. You will learn all the basic tools and best practices from the start, instead of having to break bad habits later down the road. I also like going through similar material from different people to get multiple perspectives. I feel like more perspectives you learn from the more likely you are to have more well rounded knowledge, and of course repetition is good for learning as well. Here a couple beginner python tutorials I like:
Corey has a very in-depth tutorial from basic to more advanced python concepts. He also has videos detailing setting up a development environment and word processors for python development. For another perspective check out pythonprogramming.net as well. Both of more content beyond what i have linked and I recommend checking it out.
If you are interested in pursuing the python certification I recommend using the free python courses on https://edu.openedg.org. These courses are are more text-book style learning and are even more developer oriented than the two previous recommendations. That makes it a little bit tougher, as a lot of their examples are tougher to understand due to the more pure developer perspective. However the material is still pretty good and you can get a discount code for the exam after completing the course.
I think it has yet to be seen if the python certification has any weight on a resume but, if you are like me, having something to work toward helps keep motivation up.