One of the best off page technique is content building and promotion. It helps to optimize your keywords and build good ranking for your website in search engines.
All Link building techniques will remain same but you only need to focus on quality work. Don't use any bulk link building software and get only relevant back links from Forums, Web 2.0, Social network sites..
Off page Techniques like : Article Posting, blog commenting, directory submission, Forum Posting, social media marketing, Press Release Submission etc.