It all starts with quality.

Period.

Give me something that's going to make me look good. Don't make me look like a schmuck to my subscribers by repackaging information that they could have gotten elsewhere. It should be an original product with some new information that is actually worth the money they are going to pay.

Now if I see more than one product that meets this criteria, then I'll look at things like sales copy and conversion rates. But you can have a 75% conversion rate - if the quality of the product is poor, then I'll probably pass.