To learn the art and science of SEO (search engine optimization) it is my belief that the best source is your own efforts at hypothesis, experimentation and refinement.
If you’re starting from scratch and really have no idea what SEO is, then certainly one of the popular SEO books would be a appropriate as well as attending an industry conference like SES, SMX, Pubcon or a regional event.
Both Google and Bing have made great efforts at providing webmasters with resources that are worth checking out as well. Online SEO training like that offered by Market Motive (affiliate link) can help those without the time to attend “real world” events.
Guides about internet marketing tactics like Search Engine Optimization can be very useful tools; not only for practitioners to gain insight into what’s working and what’s not, but also for the agency/client side people working on the business side of things to understand where a particular tactic fits within an overall online marketing program.
We recently posted a list of over 
Over the past few weeks TopRank has been conducting it’s own search of sorts, for a Senior Search Marketing Manager as well as a Search Marketing Strategist. One of the questions we ask is, “How do you stay current with tactics and strategies in the SEM space?”. It’s a good question both for hiring agencies to ask as well as companies that are 
