I got a lot of spam-like emails from SEO sites so finally I decided to ask my questions and got on a call with one of them, the largest SEO company in India they said.
Here are some things they do that don't violate any of Google rules:
- They submit your site to directories, manually
- If you have original content like articles, they submit your article for consideration to various publications, again manually
- They add your site to a few "directory sites" they own (gray area here in terms of quality of backlinks).
I hired a media/pr freelancer to work on #2 (these guys work on retainer, and dont guarantee results so not cheap) and didn't quite get results I had hoped for.
My point is - whenever you hire someone to do something critical to your business you need to understand the task well and set expectations on what exactly will be done, be it offshore firm or a US-based one. Educate yourself on the task to an extent that you can, so you don't get surprised about results.
If you talk to SEO companies in the US, backlinks are the thing of the past to them (I dunno, they seem to matter) since page rank is one of many factors contributing to SERP as they focus on social media these days - Likes on Facebook and Twitter follows signal to search engines that your product/site is of quality.
Facebook is now running a promotion for Small Businesses and gives away Facebook credits for meeting some milestones - search for "Facebook Small Business Boost", great way to boost your likes on your product page.