Best Place to Advertise for Free Online?

[Coco]

I have a book I'd like to share with the world, and advertise. I've read up on the subject and I hear that most books don't even advertise at all, which makes sense. (I've only ever seen James Paterson advertise his books, or when the Harry Potter books were still coming out.)

Anyway!!!! I'd like to make a small fan base online, for free, to get people interested in the book. This could help a lot with sales! It only takes about 10-15k books sold within a week to make it to a best seller! And once its a best seller, just being on the list is like free advertising! (Well...more free advertising.)

I'd like to know a few websites that you think are best for creating a small following or people. Any help would be...helpful!!! ^_^ I'd prefer if it was the kind of website with lots of free browsing going around, so a person could stumble on my page more easily.