I started a few months ago myself reading the mentioned guides ( I had them printed). I tried a little simple trial and error for a week or two and then I set up my first project.
Nothing great, a search string generator for Google Advanced Search. But I planned a little project with defined features, behaviour and all that. Then I implemented it. Whenever I had a problem I searched the forum, sometimes asked a question. And finally after two month had a working little app on Google Play. A routined programmer would probably do that job in a couple of hours. But I went through all steps from planning to coding, debugging, and publishing the apk.
It is not important what kind of project it is. It may be a very simple app, but do a complete project!
I think this is a straight forward approach and better than just playing and tweaking around with existing code (which is prone to cheating yourself). You definitely have to get your project done and reach a previously defined milestone as a control. Then do your next and maybe higher level project - and bring it to an end even if it takes a lot of time.