If you are a music lover, it would be a good idea to promote it over books and even other products. All you need to do is listen to clips of a full album within a short period, say 10 minutes, get a good feel of it without you purchasing it and do a short review. If there is another niche you are passionate about, make sure you get a unique discovery about it. Of course, there are hundreds of thousands of reviews about these products all over the web but you need to make yours more unique to attract people to your site.
And what about joining another company's affiliate program? It's all about extra revenue. Think about your customers' needs: What other products or services would interest your site visitors? Join those affiliate programs. Affiliate programs can increase your sales with no upfront cost to you. It just takes a little time to plan your strategy and select the partners that will have the greatest impact on your business.