SEO advice for bootstrapped startups

"Do not rely on SEO to market your product" Couldn't agree more. A good marketing strategy requires diversity of channels. Naturally, unless you have a full-time person working on marketing, you will have to make sacrifices, but relying on just one channel is really going to hurt your business.

"Add a free feature which is accessible, useful, and spreads virally. It can create a stream of links and mentions that quickly replaces an ad budget."

Aaron Wall makes a great point here. Creating the feature or resource is often a lot of work upfront, but over time it will turn into a better investment than churning out blog posts (that doesn't mean you shouldn't be blogging or creating content in some other form, though).

Great advice all around here - personally I'm a big fan of not "doing" seo but instead just making sure things are running in an SEO friendly manner.