You should also be very engaging with your users in social media, especially G+. It takes a lot of time, but if you don't do it, your competitors will.
This is probably the lowest-hanging fruit and the way you'll get the best results with the most accessibility. Making a social profile costs you nothing except time and creativity. It just takes work. But guess what?? That's what most people simply will not do - put in the work.
So claim as many keyword-rich social profiles as you can, and
build them up. You will need to find the best sites to do this on (yourself) but here's a hint: look for social sites that allow you to participate. (Think of sites on which you can comment on other profiles or in some way get
your profile name linked from someone
else's profile.) It should go without saying (but I'll say it anyway) that your profile page should of course link to your site.
Also, remember that if you want to participate in social sites for the social aspects, the goal is to get access to other people's fans. So try to influence and connect with the influencers. You'll waste less time by doing that - as opposed to building up your own fan base.
In the last month or so, I have seen some positive SERP movement by almost solely engaging in claiming KW real estate as I described. I simply go to a social site, register a profile with one of my keywords, build a kickass profile (all by hand, and all original), and start participating on the site to get my profile indexed. I periodically continue to participate so my profile will gain authority. You know what I ultimately want? I want one of the most valuable profiles on that site. And I want my profile to stick - which is why I put actual effort into it.
Do this one thing, and I can pretty much guarantee you'll have success.