The best place to start is with what you want them to do.
Social Media, Product Feedback?
You'll want to find someone who is interested in your product and fits with your brand message
Use our Social Insights tool to find them and see if they're talking about your competitors
Take into account reach (followers) and engagement (% of reach)
Location is important here; athletes are often busy during the season so someone in or near your city is ideal
Sports; during the season is the time you really benefit from them being in the spotlight, so leverage this
Budget is always important, so be realistic of who you can get in your price range once you know what you want. Unfortunately we can't all have LeBron James being the face of our pizza franchise.