Just remember - Reciprocal leads don't count for SEO. Google made that part of the algorithm years ago.
I have found guest posting to be my biggest help lately, especially from sites that already have steady traffic.
Nice tips, although article submission has lots some of its portency, it's still respected by the search engines
Networking is a big one. Write guest posts for other websites and bloggers to develop a name for yourself. It's a win-win situation.