Here's something I've learned about doing affiliate marketing with your blog: you have to be patient.
You may go days with low sales (or in my case, no sales), then suddenly have a big day that makes up for all the slow ones. Sometimes I get a little restless after a few slow days and start thinking about starting a new advertising campaign, etc.
But I've learned to let the process work. I'll keep getting traffic if I keep writing good content. As long as I'm consistent, the money will eventually come.