There is an article form Source Square looks specifically at SEO for the Twitter page. The author of this article details the five steps outlined here:
1. Use search engine-friendly keywords in your Twitter name.
2. Use reader-friendly keywords in your Twitter name.
3. Use keywords in your “more info” URL
4. Flood your one line bio with keywords (while maintaining natural readability)
5. Tweet quality contents, and build lots of links
It stands to reason that similar tactics to those listed above could be applied to Facebook pages as well (or other social networks). It’s all basically just good old fashioned SEO practice. Keywords, quality content, and links. You probably think about this for your website, but it is often overlooked on social media profiles.