as cliche as it sounds man, "dont give up". in 2010, i touched on IM for a lil and only made 15 bucks took a break. this past summer, i put aside my music to focus on I.M because i am graduating college next fall and I didn't want to just come out of college jobless. I' tried sooo many methods, I tried amazon sites, bought 4 domains; one got sandboxed. the other only made 4 dollars, then these past two weeks i tried another method [ non amazon] and made $4000 these past 2.5 weeks [ with $0 investment]. this was a very happy moment for me, because i have been trying very hard, and i have felt the same way you feel now. overall, if i stop earning today, I can re-invest and continue on to something new. just keep it up man, and SPIN methods. a lot of times, the methods that are posted now are aged, and the direct word for word method wont work for all. The best method lies within your brain. Once you have read enough and understand how the internet works and how conversion funnels work, you will be able to earn.
As for investing money, put that money away, just save it, until you have found a method that is really eye opening and has made you money with no investment, THATS when you should invest in the method to scale it, as others have said.
Overall, keep at it. My main goal is to be free from a 9 to 5, as im sure many others share the same goal.
P.S, im still a newbie