The biggest mistake I see being made by online marketers today is pursuing only one tactic to the exclusion of others. Some people focus only on SEM and ignore social media, some who focus on analytics optimization ignore viral content, and some focus only on PR to the exclusion of SEO. Each tactic has its pros and cons, and those who combine two or more tactics in their efforts see their results multiplied. For instance, SEO and public relations should go hand in hand. Public relations is a great way to get new links for SEO and SEO is a great way to get word out to people who are interested in your product or service. Be smart and layer these tactics on top of each other.