Crush It by Gary Vaynerchuk is a good place to start. Be warned that most people have no idea how to work social media and over-complicate it to the extreme. VERY few businesses are able to do it successfully, particularly because it is much more suited (no pun intended) for a small business like your own and very hard for larger companies to take advantage of.
The fact is most people don’t discuss commercial matters on social networks. Whenever someone posts something promoting their own product and brand it instantly turns the reader off. Instead, people like to share funny or useful content rather than specifically talk about a brand or product.
Let’s say you wanted to work LinkedIn. LinkedIn is a site for professional connections. Your business sells discount custom suits and fashion recommendations (I believe?). I think it is a safe assumption that people who are potentially interested in a suit coupled with fashion advice are likely going on an interview or hoping to go on one and want to dress to impress.
In order to target this audience on LinkedIn or Facebook, you might create an article entitled “12 Things You Must Know For Your Big Interview” or “The 7 Key Rules of the Perfect Interview” and go on to discuss 12 tips or 7 rules - it doesn’t matter as long as it’s good. Naturally, part of a good interview is dressing the part, so one of your 7 tips should be like “buy a nice suit” and recommend your own company as an option.
To increase engagement, you could put in the article that you are happy to answer questions through Facebook on your fan page. Make it an enticing offer - let people send you their picture dressed up in their interview attire and offer free advice and post it publicly. Now you are interacting with potential clients and customers, and when they decide to buy a new suit, odds are they are going to go with the guy they “know”, even if you just met online.
At the end of the day outside of what networks to sign up for there’s not a lot that anyone can tell you since it’s all so specific to your business. What I can tell you is that people like good content, whether it be in text, audio, or video… people winning on social networks are producing useful free information that people like to talk about. They aren’t just creating a facebook fan page and posting useless crap over and over again that no one cares about (99% of companies).