I've recently started work on a new site. The goal is to have it profitable in 12-18 months (selling affiliate products related to travel through SEO traffic). I'll be adding only1-2 pages a day (written myself, decent quality). But I think a lot of the promotion techniques I've used for earlier sites are less effective now.

I'm only interested in getting targeted SEO traffic, not thousands of uninterested visitors.

At the moment I submit an article (eg to ezinearticles) for each page I write, and sometimes link from other sites I have myself.
But which others of the following would you focus on most for link-building?
- free directory submissions
- paid directory submissions
- in content link exchanges
- social networking sites (they seem to bring traffic but I never made any money from digg, stumbles etc even when I had lots of visitors from them)
- blog comments
- forum signatures
- should I do lots more article submissions?

I'm not interested in techniques that might get the site penalised - slow and steady progress is the target.

Big question, huh! All advice gratefully received