Social Media gives a marketer great tools to better understand your ideal client. By joining the social networks where your ideal clients hang out and taking note of the products/services they are interested in, you learn their wants and needs. And that helps you offer the right products/services.
Each social media platform has specific search features, but in general, take note of the users your ideal client is following, re-tweeting/sharing and commenting on.
What Facebook Pages does your ideal client Like and leave comments on?
What Twitter users are your ideal clients Following?
What Pins are your ideal clients Re-Pinning and what Boards have they created in Pinterest?
For some great tips and specific steps on using social media for market research, check out this article from Social Media Examiner: How to Use Social Media for Customer Research