Hi,
I am not currently on Goodreads so I cannot comment on that, but I am really benefiting from Facebook.
It was touched on, but whether or not you get a Facebook profile depends a lot on your target market, your own age and you current use of the social networking site.
On target market:
When I decided to self publish a number of months back, Facebook was high on my list of priorities. On my personal page, I would have close to 700 friends, and I hoped that at least half would click 'like' on my author page when I created it. As this is my first published work, I used Facebook more as a method of spreading the fact that I write, rather than directly or indirectly selling books. An older age group will buy something physical that is placed in front of them (which is why I stocked in local stores) but, the people that follow my author page are more used to, and more likely, to buy online (As in order PB or kindle version)
And, as that is where I think I'll benefit most in the future, I put special emphasis in promoting my facebook author page.
Your own age and place on Facebook already:
Please don't accuse me of ageism! And, I'm not saying you have to be known before you make a facebook page!
- Put it this way: If you were a celebrity with 20,000 'likes', your audience is already massive. OK, the majority of them may not buy what you're selling, but 5% of 20K is better than 5% of 25 eh?
And, at the other end of the scale, starting out your social networking life with no existing presence is a difficult task. Me, I was somewhere in the lower ranges, but above zero.
In conclusion, I think that if you are starting from zero on Facebook, twitter, etc, I would recommend concentrating more on Goodreads. By all means, start up your author page on Facebook but don't expect it to work miracles from day one.
To each their own, it is just that Facebook has worked very well for me so far. Check out my self-pubbing diary if you've time, it may help with Facebook ideas etc.
I hope that helped, I may have started to ramble
Best of luck.