Referees are your personal sales-people so you need to make sure you have chosen wisely and leveraged value from the conversations they will have on your behalf.
Your current workplace may be a no-go zone though a trusted colleague might speak for you without blowing that you are in the hunt. Former bosses are a staple but also consider peers in other workplaces; clients and customers; people who have trained you or been trained by you and personal contacts who know the industry.
