I would first look at where your advertising dollars are being spent now.  How do you measure and track your clients?  Where do they come from? What is your target audience?  Before spending any more money......see what is working and what is not.

A competitor of mine bragged three years ago she hire a person just for social media, twitter, facebook and things like that.  It was a big ooops.....her clients like mine are not twitter savvy or spent a lot of time on facebook.  The extra expenses associated with trying social media almost caused her business to go under

Now don't get me wrong there is definitely a place for social media in almost everyone's advertising budget.  You just have to find one that gives you the most return for your buck