I always use a landing page which is a generic template that I use for all testing. As soon as one sale comes in I'll customize the template to make if more inviting. Also don't forget to add a Privacy Policy page and link it in your footer. This will also improve your quality score.
If you are doing PPC advertising, you generally (95% of the time) need a landing page. Also, I would go a little beyond a Privacy Policy. I'd add a Contact Us, About Us, Terms, and Site Map if you really want Google Love. Finally, don't forget that Google is getting more strict on affiliates. They just did a quarterly slap that really messed up quite a few super affiliate campaigns. I'm starting to make all my sites Authority sites by adding articles to them, message boards, etc.