I have seen many people when they are told that advertise your gigs on social media so they start asking that how to advertise on social media.
Here is the answer that how to advertise. I have seen the results where impressions, click and impressions increases so fast by applying this method by myself.
I use twitter for advertising where trends can be seen and trends are those hashtags which come up and down depending on how many people are tweeting using a hashtags at that time. So you can tweet your gig link with using different hashtags by which your tweets can be seen on wide area. Change the country of trends to US, UK, Australia and Canada and use hashtags of that country in your tweets.