Facebook, Google+, Twitter, Linkedin all are great but before selecting anyone or two or many social sites, you need to ask by yourself that, why you are in
Facebook
or
Google+
or
Twitter
or
Linkedin
Maybe you can get your customer in some particular social site. For an instance, Twitter is a short message service provider and surely it is also great media through which you can easily get the traffic and popularity. So when you select twitter you need to care for 3 core elements
1. Headline
2. Link
3. Hashtags
If you have any query please ask without any hesitation.