The rise of social media has seen a big increase in the use of brand influencers. In the last two years, “influencer marketing” as a search term on Google Trends has risen by 400%. But working with the right sort of influencer is critical – you must choose one which fits well with your brand and has an authentic voice. Biggest is certainly not always best when it comes to influencers.

Pepsi’s controversial ad from last year is an example of a brand not quite...