How and why do you structure a social media campaign for your brand?
Social media campaign tends to last longer and have a larger potential than a simple social outreach. When recruiting fans, customers and strangers though, you have to think about a mutually beneficial relationship.
Your brand ambassadors should get something valuable, in exchange for promoting your company. Don't be afraid to ask what they might want.
The value you give them does not have to be monetary, but could instead be excuse access to features or events, or even just a public recognition of their value-add to your company.