Marketing, promotion, reviews?

 Almost every second of the day I am trying to understand how to 'exist' in the eyes of the public. I want to sell books because I love writing and I want to continue, but without sales there is no growth; without sales there is no money and therefore no time to write.
I get bombarded with options from individuals on twitter, from big companies, from start-ups, from Facebook and Google, and yet I cannot decide which way to go. This is a problem.
I have even thought of going to the fairs such as the Frankfurt and London fairs, but all that is just more money and no guarantee that anybody else will know you exist. I did get an email the other day with some interesting articles on how a small start-up in San Francisco is blogging about how they are growing and what they are doing and one of the good things I got from this was the foray, ever-so-slowly, into advertising on a very small scale. Basically, they dipped their toes, so to speak into varying types of advertising and marketing to discover what worked. None of these cost them very much at all.
If anyone has some definitive answers or amazing turn-key solution, we'd LOVE to hear it.

Ciao

The Editor