Social Media is the biggest thing to hit online marketing since the advent of Google. There are so many different social media sites nowadays that it can get really confusing as to where you should be spending your time and effort. Obviously a great starting place is to work out where your audience/potential customers hang out online, i.e. which social media they are using. As a very rough guide:

• Twitter is used for work and leisure.
• Facebook is used for leisure and work, can be very good for local business marketing.
• LinkedIn is primarily business focussed.
• YouTube is used for all sorts of videos.
• Google+ is used for work and leisure.

There are other sites that may well be relevent to your business too, in the UK these would include Instagram and Pinterest.

Word of Warning

You are much better off doing a good job of marketing high quality material on one social media platform, than you are doing a poor job with lower quality material across multiple. Also please remember not to just advertise at people all the time. Help other users of the social media platform you are using, join groups, answer questions, ask questions, and occasionally offer your/your companies services (in other words advertise).