The reality is that most startups won’t succeed, but with failure comes knowledge and the co-founder of one failed startup says online marketing is one of the most important things for a website – if it’s done correctly.

Mark Goldenson was the co-founder of PlayCafe, an internet TV network for games which failed when the site was unable to reach enough users. In a column for VentureBeat, Goldenson assessed what went wrong and what went right for the site and says marketing was the main failure of the startup.

Goldenson says that the company’s efforts to using search engine optimization (SEO) and search engine marketing (SEM) weren’t "terrible," but says that online marketing requires more professional help.

"Like creating content, I no longer think marketing is something smart novices can figure out part-time," he wrote. "As the web gets super-saturated, marketing is the difference-maker, and it’s too deep a skill to leave to amateurs."

Search engine optimization has become something everyone with a presence on the web is starting to consider as the online landscape becomes littered with sites. A recent report from Internet Retailer found that 55.3 percent of respondents said they plan on increasing their search engine optimization (SEO) spending in 2009 while only 24.2 percent said they plan to increase paid search.