Article postings.
Directory submissions.
One way links.
Two way(reciprocal) links.
Three way links.
Social Media Communication.
Book Marking.
Press Releases.
find out your competitors on a certain search term then use backlink checker tools (there are free tools online) and see who links to them and submit your site too. It is advisable to exchange links to sites already indexed by search engines.
Both have to be done simultaneously for it to work perfectly. I think it would be best to generate plans first. Jot down keywords, optimize your site, make a good landing page, and then gather some link backs...