Justin pretty much summed up everything you need to build a solid foundation.
What I would do in the mean time is create two different landing pages and use Google Web Optimizer and then throw some money in Adwords just to get the highest conversion optin page.
This way you can get more out of the traffic you are generating from the articles, press releases, etc...
I find it very valuable to split test the optin and sales page before I even start my campaigns.
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