Google "What is Pligg" you should find lots of pligg sites where you can do social bookmarking..
PS: Pligg has been dying lately coz of link spam. not many good pliggs out there.
I would like to suggest why Facebook Page.
I would not go for FB groups, guess why? Google cannot index FB groups. On the other hand it's easy for Google to index FB pages.. these are open for SEs..
IMO, below would be high quality backlinks
1. The source and target of a Backlink both should have same niche.
2. The source and target, both should have unique content.
1. Post rich and unique content.
2. Share your blog posts on social sites w/ your friends and friends's friends and so on.
Also submit your blog to blog directories.
If you are doing SEO for a site, that would imply you want organic traffic from sites like Google
On the other hand, if you are doing SMO, you are targetting social networks like Facebook
Now let us say, your product is a game like "Candy Crush", you should be deploying 80% of your efforts on...
It would be noteworthy that, IF your site consists of only page, the bounce rate would be 100%, no matter how interactive your site is and how much time a visitor spends on your site.