Know-How Exchange : Customer Behavior

I keep hearing that word of mouth communication is the most important influence on customer behavior, due to the fact that everyday there is always a conversation about a product or service. Also because it's strong effects on the later stages of the purchasing decision process. Consumers are more likely to adopt a product if they have heard good WOM communications about it, and will throw away a product immediately if they hear negative WOM.

The question I am posing, is how are marketers supposed to have other sources of communication such as personal selling or advertising be more influential then WOM?