Are you on Twitter? Can I add you on Facebook? Do you have a blog? These questions are quickly becoming the currency that occupies the same space that business cards do. Colleagues, customers and other contacts expect to be able to keep in touch with you in between business deals and social media is the way to do it. But which social media platforms are best for your business?

There are almost too many to choose from. We could fill up this entire page with social networking platforms and social media outlets—there are that many—but for now, let’s stick to the big five:

Twitter is a traditional media darling, which is a bit deceptive. You’ll read about Twitter at least once or twice a day in The New York Times or The Independent, which may make you believe that being on Twitter is an absolute must. But that’s not necessarily the case.

Twitter is best for light networking—that is, getting in touch with industry contacts, keeping up with relevant news and reaching out to new and current customers. It seems highly approachable on its face—all it takes to tweet is 140 characters. But therein lays the danger.

Twitter is relatively harmless for casual users, but for businesses, it demands strategy. You can just have any intern manning your company’s tweets, since it’s far too easy to fire something off that you’ll regret or that will misrepresent your company. Tweets seem fleeting and ephemeral but they’re not. They show up in search results, are archived on the server and may even end up in the Library of Congress.

The key to Twitter success is painting in measured, spare brush strokes. It’s a delicate social game of hat tips, horn tooting and classy shout outs. Too much self-promotion and you sound like a shill. Too little activity and you may as well be invisible.

While your mileage will certainly vary, Twitter is best suited to companies with a high level principal or executive who can devote their time to crafting insightful tweets or a company with a social media consultant.

Facebook has the biggest audience, which means it’s apt for big companies. Facebook for businesses is set up so you work towards garnering "fans.” For this reason, dominating on Facebook is more a matter of brand strategy and slightly less a matter of communing and chitchat. Facebook is a great place to promote your high profile events—live webinars, sponsored bashes and product launches—but you want to ensure that you have enough cred among your customers to actually garner a following.

Whereas Twitter and Facebook heavily skew the personal and professional ratio to the former, LinkedIn is the opposite. LinkedIn is mostly about business and depending on your goals, that can be a good thing. LinkedIn gives you access to experts and consultants who you may be able to tap for advice or a new hire. Plus, you can keep tabs on the career moves of important contacts (it can be tough remembering what department someone was in five years ago, especially if it has changed).

Foursquare and other location-based social media is obviously for businesses with physical establishments. But it’s also for businesses with a relatively tech savvy customer base and audience. Foursquare isn’t even close to critical mass yet, and even some iPhone junkies won’t bother to check the app every five minutes. Plus, getting on Foursquare takes a little bit more effort than registering for a free account at LinkedIn, Facebook or Twitter. But with that being said, Foursquare is relatively untraversed ground and you’ll definitely get noticed, if there is anyone there to notice you. For now, Starbucks seems to be dominating the "nearby deals” playing field, which means there’s plenty of low hanging fruit to be captured in mobile marketing.

Checkout Foursquare for Businesses for more info.

Company blogs are your place to show your expertise and say something meaningful and unique. There is undeniable value in maintaining a strong company blog, but not everyone can do it. You can’t fake being an expert, in other words.

Before you start strategizing a company blog, make sure you have a deft wordsmith on board (if it’s one of your principals or managers, even better) and that your two cents is even valuable. When it comes to long form analysis, how-tos and guides, you’ll likely have some heavy competition, depending on your field. For example, you’ll have to be pretty sharp to scoop Gizmodo or Wall Street Journal. But for more esoteric subjects, such as commercial piloting, plastic surgery or tool and die casting, a well written, enlightening article can help you stand out as an industry leader.

While there are a number of ways to use each of the social media platforms discussed above, the key takeaway is that strategy is a requisite. Too many companies rush into as many social media outlets as they can without a game plan which typically ends up being counterintuitive. Instead of having a thriving empire of social media kingdoms, they have an underdeveloped shanty town where the lights are on, but nobody’s home. Choose your social media outlets wisely and focus your efforts on the two or three channels that will bring the most benefit to your business.