Create your content using your targeted keywords but still look interesting and useful for your readers.
Personally, I like Jon Leger's "coolest guy on the planet" experiment. It's easy to understand for not-so-good-at-SEO- people like me. But I just look up to Jon cause of his instant article wizard. Heck Yeah! Makes my job easier.
This is the big one, though. Most people OVERSATURATE their sites with too many keywords, when Google is now looking at related phrases. I wouldn't know exactly what, but if it's relevant, Google sees it as such as well. It just takes some getting use to. We can't link bomb the sites anymore, because Google now sees if we're using relavant topics or not. And not just keyword dense, but topic dense. I think it's sexy.
The key to high rankings on Search Engines is Link Building. You should read this Link Building Guide for tips on getting links. Even if you have a very good site with lots of content, you cant just expect it to achieve high rankings by tweaking your Title, Mets and other Tags. You will eventually need to do some kind of link development for your site, and use the important keywords as anchor texts to achive high rankings in SERPs.