Don't be afraid to ugly up your site a little bit to make your Adsense ads really stick out to get a better CTR. You'll get a few complaints, but the increased CTR will help you sleep better at night.
This is one point I can not agree with. Remember "think long term". You want other webmasters to link to you; to increase traffic and popularity. If your site looks like "Made for Adsense" you’re not going to get many natural links.