The key is to be true to your community's norms and values. You can't just force yourself on people and try to sell them something they don't want - that's good advice for marketers generally, but particularly on community-driven sites like MySpace. You have to find ways to add value to your members' lives while being consistent with your brand's identity.
Source: Business 2.0: How To Succceed: Keep Social Networks Social: http://money.cnn.com/popups/2006/biz2/howtosucceed/2.html
Contributed by: ~C4Chaos