Twitter does seem more helpful and hashtags are very useful as these put your post on various lists. For authors the following hashtags are useful, but are not exclusive. I'm sure there are many more so feel free to add to this list.
#books #read #readthis #booklook #review #shortstory #bookreview #samplesnday #storyfriday #fridayreads #iartg #writertip #writingtip #selpubishing #kindle #freebook
However, Twitter posts scroll very quickly down the page so disappear from view fast.
Aboutme is a useful page to have and people look at this site without doing to much work.
LinkedIn is mainly about seeking jobs, I think. I am on that but not very active on that forum.
My blogs are setup to always post on Google+ but that is one site I rarely hear from.
Pinterest is useful but the information you can post is limited, unless I am doing something wrong.
I have not tried Instagram but a colleague who is a very active photographer uses it a lot. It's really about showing images and photography is good as you are getting new images to show frequently. Having a few book covers may not suit that media, in my view. For a fuller list of social media sites try here
My experience is that Social Media is nice to have but won't necessarily drive lots of people to your website. Facebook messages, for example, will appear in front of the same people over and over and it is likely that, unless the message changes, they will become bored of it. I haven't yet spent money on advertising on Facebook but from the response from other people it is not always money well spent.
I am not advocating not using social media but pointing out that expecting instant traffic is unlikely and one problem is you can commit a lot of time to it for little reward.
One irritation I have is there are lots of posts on the Internet about book marketing and many spout lists of things you must have such as an author's website and being active on social media. That is so easy to say and yet how to direct traffic from these sites is actually very hard and at that point the advice dries up.