When it comes to marketing, it's hard to know what actually moves the needle, but that said, SCBWI's Book Blast is fast and cheap. They provided a template; I filled in the information and paid $25.
At last check, more than fifty people had viewed the Book Blast Page for RUBY LEE AND ME. You can see it too by clicking here:
Several of my friends also have Book Blast pages. Take a look at BEAUTIFUL by Stacy McAnulty and THE FIRST LAST DAY by Dorian Cirrone.
Do you have a Book Blast Page? If so, post a link in the comments below, and I'll check out your page too!