most affs presell on their own landing page before sending user to offer page.
If you are doing adwords, send clicks to your presell landing page and make sure to use this basic set of quality score best practises ::
1) include the KWPs on your landing page with appropriate density
2) Include an xml sitemap in your footer and register it with google webmaster tools ::
Google Webmaster Central
3) Always include at least one outbound link to related relevant content on a page that is included isomewhere in your site / sitemap. I usually just select something from wikipedia, and hide / bury the link. It's a traffic leak, but it's there to beat the quality score.
4) at least two 500 word articles on their own pages of relevant content with an appropriate keyword density.
5) core keywords in H1 and H2 tags
6) privacy policy
7) physical address in footer
that should do it ...
these are the basics of running a google-acceptable "thin affiliate."