Would it be better to rank a sales page (aff page) or a page that describes the product in your own words and then have a link to the sales page (aff page)?
Yeah, it's best to pre-sell the visitor and get them interested in the product, then move in for the kill. At least this is the case with my experience.
If you're talking about search engines and organic traffic, then yes, the second one is better. What you get from the search engine is basically leads. The sales page would generally hard-sell, and this doesnt always work well on cold leads. If you 'warm' the leads with a pre-sell, which legitimises the product, then you will get more sales as an affiliate.
Try to create a web page that describes the product in your own words rather than raking content from the sales page of the vendor site. that gives a good impression to your visitors and also to search engines.
second one for me. I use seo to my pages so i earn not only at clickbank but also at adsense. see my sig.