Social marketing does not help much if your business clientele is outside the tech-savvy demographic but for most businesses, social marketing strategies that are correctly done can be very effective with virtually no cost at all.
Take advantage of the available platforms and their capability to integrate with others. Avoid duplicating your maintenance effort by centralizing your active participation on one platform by setting automatic synchronization with others. For example, link up your Twitter account with your Facebook account so that information needs to be posted only once. Build your brand by making your account IDs consistent whenever possible and advertise them widely.
Once you setup a few accounts, set aside only a few minutes each day to offer deals, share your expertise and connect with your existing and potential customers. Remember that being responsive and helpful online is just as important as is offline.