Having spent a few years trying out a whole range of writing communities and general social media and networking platforms, I believe I've isolated those that are worthwhile and dropped a huge number that are a waste of time. I realise that we're never going to all agree on these and that some people are better suited for some than others, but here are my results in reverse order:
Still struggling with this one but it is the second biggest author community out there. I find the reviews can be a little unhelpful - it's one of only two places where I've received any negative reviews with no attempt at being constructive, but still mostly friendly and helpful. I don't like the forums here and have never felt like part of the community. Worth adding all your books here. If you make any decent headway, please let me know how you did it! Visit GoodReads.
This one is only on the list because everyone would think I was crazy if I didn't. I have to admit I just don't get on with Facebook. The interface is confusing, cluttered and unintuitive. In all the years I've been there, I've gathered just 9 followers. That's about 3000 times less than Wattpad and not much more than a third of my Minds following (and I've only been there a few weeks). I keep persevering with Facebook but it's not been of any benefit for me. Visit Facebook.
I know many people would rate this one higher but it's been problematic for me. For the first few months, it worked and I got on with it very well. I gathered lots of followers and seemed to be doing well then it all died. I've only gained about 20 followers (yes I know the jargon is "20 people added me to their circles") in the last 6 months, but I'm still trying to make headway there. Visit Google+.
This one is very much the new kid on the estate and it's probably too early to say if this one is going to be a hit, but their interface is great and the social aspect of the community works very well. The writing community is only a small subsection but it is only just starting out and growing fast every day. Activities in the community such as posting or voting gain you boost points, you even get 50 points per hour just for visiting. These points can then be used to boost your points - great for your next big book launch or competition! Visit Minds.
Twitter is simply massive. Everyone's heard of it and (almost) everyone is on it. Better still, unlike some more restrictive social networks, it's easy (and totally permitted) to have more than one profile there. You can have a personal account, an author account and some authors even have accounts for their main characters too! The main drawback with Twitter is that there's too much activity and once you're properly engaged in the community you'll receive far more tweets than you can read. However, follow the right people and it's a great way to find out about publishing opportunities, writing competitions and lots more, all while connecting with a few readers along the way. Visit Twitter.
I really wish I'd discovered this year years earlier. Excellent site for connecting with a simply colossal number of readers as well as other authors. Highly active and friendly community with forums, competitions, rankings and a comprehensive comments systems. I've made more contacts here than anywhere else and it's a great place to get feedback on your writing. Visit Wattpad.
No doubt I will be adding more to this list in future and, of course, I will rename the post accordingly. If you have any suggestions for writing communities or similar that I might not have tried yet, please add them to the comments below. In the meantime, I hope this list is useful to you.