(via “DONOTREMOVE”:http://donotremove.co.uk/) Wordtracker have published a 75 page PDF on how to conduct successful keyword research.
Although it primarily talks about how to use Wordtracker for your research (and uses a fictional online vegetarian dog food store as its example), there are a lot of tips and advice from SEO and copywriting experts that can be applied in more general terms to this topic.
If you ever have a client who doesn’t get why keywords and content are as, if not more, important than design, there’s a good overview on pages 9-10 on why keywords matter.
The guide also reminds you to optimize your copy for your human visitors as well as search engine robots – a fact often gets lost in articles about how to top the search engine rankings.
In addition, on pages 68-71 there’s a useful/yet another (choose your adjective depending on your level of knowledge) checklist on where to use your keywords on your site to gain maximum effect.
“View the keyword research guide”:http://www.wordtracker.com/keyword-research-guide.pdf (PDF).