Social media isn't about promotion when you are a small business. It is a medium for interaction with your existing customers. Any promotion that is done is an after effect of the work you put into social media.
Be completely frank with yourself about your expectations for social media. Spamming a bunch of links on Reddit or getting a ton of Facebook likes will get you absolutely nowhere, and I've known many companies blow thousands on spreading low-quality links and buying tweets and Facebook likes, and they've earned the best part of £10 at best from it. Unless you're a huge company you will NOT get loads of visitors from your social media campaign.
The best thing I can recommend for you to do is to use it as your communication channel for your existing customers. Keep users updated not too infrequently, engage in conversation with those interested in your product, joke around with it a bit, and so on. These are the best kinds of social media campaigns and it'll pay off well for little return.