
Start by finding every place on the Internet that is relevant for your product or service. Identify all your current positive articles and bookmark them. Create all the social profiles that make sense and start participating. Join relevant forums, create directory listings, start commenting on blogs, answer questions at Yahoo! Answers and Linkedin, and start a blog with good content. Start a press section on your website and link to all the mentions of your website (that you want to promote) for everyone to find when doing research about your company.
Turn the Ripple into a Wave
Send out a press release over the wire that includes an interesting topic, company milestone or other press release worthy information. Bookmark all the new articles and locations for that press release. Continue to create ripples with social media participation, blog comments, new blog articles, directory listings and Q&A participation.
Turn a Wave into a Bigger Set of Waves
Continue sending out a couple more press releases that are interesting and informative. Continue to promote them on the Internet with bookmarking, social media, directories, blog articles and Q&A. Get a fair amount of visibility everywhere your customers and relevant industry online journalist will look to find additional info about your company and website.
The Tipping Point
Once you have created a pretty good set of SEO waves, launch a press release that is monumental, offers information that is a must have for anyone to read about, or choose a topic that you know will get major syndication in your industry. Now that you have created a bunch of waves and everywhere an online journalist goes they see your website, it is time for the Tsunami. Push the monumental press release with as much external power as you can (bookmarks, social media, a blog article, etc). Contact the who's who in your industry about this serious press release. Leave no opportunity on the table, this is the tipping point.

Most SEO professionals will stop and say, "I have done everything what else do I do now?" Don't let the momentum fall off. Keep promoting your press releases, positive articles and press section. Keep getting links, mentions & trackbacks. Keep finding new articles about your website and promote them externally. It is much easier (and cost effective) to sustain SEO momentum, than it is to create it.