Hello friend, forum posting,article submission and blog commenting are good for traffic and social bookmarking is also good.
One of the best long term waytoo continually generate link to your site is by creating resources worth linking to. I have also distributed templates which carry backlink to my sites.
One way to increase traffic towards any website is to do submission work such as directory,social bookmarking,forums, blogs which are Do Follow..
There should be two steps to choose the best from your points. First, there should be two enteries 1. Article Submission 2. Forum Posting And No. 1 option for long lasting SEO, it should be Forum postings.
I'm suggesting the Four from your list. 1. Article submission 2. Blog creation & commenting 3. classified 4. Forum Participation