Any time we represent anything with a URL we should be using a Google Campaign Link to better identify our traffic in Google Analytics. These links are what make it possible to accurately measure our response and report on our efforts to the programs. It is key in helping us determine our ROI and whether a particular medium is worth our investment.
The following are the directions you need to create a campaign link at https://ga-dev-tools.appspot.com/campaign-url-builder/