The one thing I would say is to look very carefully at what you want to achieve via SEO. I'm fairly certain that the majority of potential customers in our sector (information security) don't want to fill in a form, although we do have a few visitors. For us our site is more about communicating what we do for our customers, than getting people to invite us to do work for them, but of course that's a world of difference from trying to get someone to sign up to a web app.
http://www.kalzumeus.com/2010/07/17/seo-for-software-compani...
I'd also suggest taking a look at http://www.seobook.com/
The one thing I would say is to look very carefully at what you want to achieve via SEO. I'm fairly certain that the majority of potential customers in our sector (information security) don't want to fill in a form, although we do have a few visitors. For us our site is more about communicating what we do for our customers, than getting people to invite us to do work for them, but of course that's a world of difference from trying to get someone to sign up to a web app.