I’d stick with Amazon if I were you. All of my Amazon sites only have Amazon affiliate links. If you use Google Adsense display ads on your site, you’re literally taking people away from your site for the sake of just a few cents with these type of ads. If you direct them just to Amazon, then you have a greater chance of earning more money from that click.
This topic is extremely broad; there are countless strategies for increasing visibility (and ultimately click rate) on your affiliate links, ranging from incorporating links into your content to sending emails to your newsletter list. Check out some of the affiliate marketing gurus on our Best Monetization Blogs overview for an extensive supply of tips and tricks for boosting the number of clicks your affiliate links receive.