Which SEO activity nowadays is better for better ranking?

[discountelemart]

Thanks to all for your valuable contribution about SEO aspect :
I did following things regularly like :
1) Forum posting
2) Directory submissions
3) Classified Submission
4) Social book Marking
5) Blogging
6) Blog commenting
These Followings work in a week
1) slide/image and video Submission
2) Social media activities
3) Article Submissions

But Still Faced Ranking Issue like huge fluctuation and most time website going down i don't no why?? so please suggest some advance activity to improve ranking. Thanks !!