Need help creating opt-in form and email campaigne

Hi

I have a 2 yr old blog that up to this point have been relying on SEO for my traffic. Like many others I get to the top of goofle...start making some money, then poof google farts and I disappear. I so over SEO as my main traffic source.
I have been doing alot of reading in WF and am sold on article syndication. I have written some article more geared toward syndication though I havn't aggresively pursued web sites who want to publish my content yet.
While I am working on more content and since I do get some targeted traffic from other sources I wanted to start building a list with an opt-in form and create a email campaigne. This is new to me and am not sure how to proceed.
I know I need to create good info and develope trust with readers, but how long shoul it be, how offten do you send it out, should I not try to promote anything at this stage. I Want to try and increase my odds of success with this so I am asking for any advice.

Thank You

P.S. My blog is about window treatments.