Luck, timing, and publisher support are at least as important as anything that I can do as an individual author.

All of this is true. What is also true, and worth considering: authors can work together, to promote their own & each other's work. I draw your attention to Murder Squad (http://www.murdersquad.co.uk) and The Write Fantastic (http://www.thewritefantastic.com), because I'm involved with both, and this is a scheme that works, it's had measurable effects on sales and profile for all of us. Though it too is not a secret handshake, and none of us has become a bestseller on the back of it...