Everywhere you go you fine links to other major sites! do you think they are helping you or just helping those sites?
I think they only help the site you are linking to and if they in some far corner of their age have a link back to you they still benefit more than you, for you are only one and they many sites like your linking to them.
Unless you are getting paid, I would not ever link to the major sites, unless in unavoidable.
Many I mean many new to the web, just click on them by mistake or to find they need to sign up and great an account their to post their links or what ever and if your site does not get many hits the only ones that gain from your link is the one you are linking to because they have thousands if not millions of links form small sites like your to them!
The only time links are good is if they are linked to you, this what helps rant your site!
Of course there are more factor s to rankings, but the issue here is links back to you, that are few!
So this being said in my HO you are feeding the big and not yourself!
the likes and links mods are only good if they are limited to your site and or some friends. In most case of the smaller sites!
regards,
Maxx