adsense sites vs. affiliate sites

I've had some reasonable success with adsense sites, but I can't seem to make any dent at all in making money as an affiliate. :-( I think I must be creating the wrong kind of site ... what has worked for me with adsense is to find a market looking to buy a product to solve a particular problem, then writing pages about things to look for in the products, how to know when they need the products, tips on how to buy, etc. Not promoting or even mentioning any specific brand or anything, all just general information. This has gotten really tightly targeted adsense ads and a good click rate. But when I do the same with an affiliate product - and by that I mean, do the same kind of site I'd do for adsense, only replace the adsense ads with affiliate ads - it just goes nowhere.

If I was trying to promote, say, Amazon products, how would I change that approach? Should the pages literally talk about the product itself? I guess I've been looking at affiliate ads as functioning kind of like ads in print magazines; the article on the page isn't exactly about the specific product in the ad, but it's about the problem the product would solve. But I'm starting to think that's totally the wrong way to go at it - any suggestions? Your advice/experience appreciated!