iowadawg is correct
1.Article Submission - Killed by Panda and Penguin. Links from poor quality content have not value. 99% of submitted articles are crap and article submission sites have been heavily penalized.
2.Social Bookmarking - Never has worked. Most social network links are nofollow. Google has abandoned social networking as a rank booster because it is too easy to cheat and manipulate results. They do not even use their own Google Plus network.
3.Forum Posting - Minimal results at best, and only if your site is directly related to the forum's primary theme and the topic for the thread.
4.Blog commenting - WordPress automatically adds nofollow attribute. If you can get people to participate and stay on topic with your blog it can be good for your own blog, but doesn't help the sites that blog comments link to.
Anything that has been overused and abused over the years no longer has any SEO value.
"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote." -- Benjamin Franklin