Originally Posted by johnny_d

1) Facebook - create a page / pages + promote in Facebook groups (related)
2) Twitter - create an account, get followers by following people following related / relevant accounts (there is a lot more to Twitter, and I still need to learn it)
3) VK.com - create a page / pages, there are groups over there too (similar to Facebook)
4) G+ - dont use it if you have xxx content on your site, I am assuming you would want to get people from there to your site, and if you have any type of xxx pics or videos, it is not good for this, they will ban you
5) Reddit - create an account / accounts (if there is a lot of accounts you may want to use proxies) - vote up and down, add comments, add links to your and possibly other content and make sure it is good (dont just add 10 links in a row to your domain, and on the top with shitty content, as it wont work; pretend to be a real user there, and submit good things)
7) StumbleUpon - open up an account, follow some people, browse some pages, add links to your sites, mix it up with something good, something like Reddit, be a real user there (there is more to StumbleUpon, I think, I would need to learn)
8) Tumblr - open up a blog, and add some pictures / videos / posts, follow other people, this is not hard
9) Sex.com - create an account there, pin pictures, you can automate it
10) Pinterest - you can use it too

All this you can do yourself, if you have time. No need to hire a company. They may charge you a lot of $$$ and it is an easy thing, it just takes time to do. Google / Seo is better than all these sites combined (maybe except for Reddit) as far as amount of visitors to your sites (I may be overestimating, as all this can add up, but it is not a whole lot, probably up to 20% of all visits to your sites combined, over time).