Just an year ago when i tried my hand at getting that initial traffic or getting the site indexed quickly through social bookmarking, all it required was to sign in and then submit a link to the SB sites. Has the process changed completely? I noticed propeller stating that it will shutting down from Oct 1, reddit i dont think has changed much, digg now requires you to gain followers (i got a message after submitting a link saying that the story has been sent to my 0 followers). When i used the SB sites initially i used to get anywhere from 20-30 visits for a decent article to 500-800 visits for a real good article. Does it now really require a lot of work to be even moderately successful on SB sites?
If you have good content, then you're well on your way. To be sure, the more followers you have the better. You can acquire them slowly over time by putting in good content but also you can have outreach and ask people to follow you.