Like any other business endeavour it all boils down to a very simple forumula.
Engage - Pick your target, Methods, and Build a Test
Adapt - Based on your test results adapt changes for improvements
Overcome - Scale what works to a size that makes money
Lather, Rinse, Repeat... - Do it again with a different product, etc. constantly engaging, Adapting, and Overcoming the competition with enough diversity that a single failure won't kill you.
If you are playing it so safe that you can't lose you'll never win. And if you are so wreckless that a single failure will defeat you your doing it wrong.
It takes patience, persistance, and perseverence to do this. Just like any other business.
You can make a grand a day.. but you've got to put in the work.