Each of those main social networking sights have HTTPS available, you just have to search them out. You can also use secure browsers/apps for browsers to help up the security for your accounts. Make sure you're seeing HTTPS up top before you go on them. It's not a surefire way to prevent being hacked, but it's another step to help avoid it.
If you cant find where to enable secure browsing, simply type "s" at the end of "http". You might have to keep typing it in for every thing you click, but most should keep it there.
Annnd for those who don't know what I'm talking about, I'll use facebook as an example:
Https://www.facebook.com