What is the best way to promote self published books?

[Sylvester C]

I am a struggling author that is not making much money off the books and not many people are being interested in them, I have tried to through Facebook and even created a twitter account to promote, I have also made a web page and still nothing. I have even gone to several Cons trying to promote and I turned out more in the negatives then the positive. So what do I do? Is there any other options and what else can I do (That wouldn't cost me a arm and a leg)