If you want to make Instagram a useful tool in your marketing toolbox, you're going to need to know how to write an effective caption.
First, know your reason for posting. If it's just to share something cool, that's fine. That tells you your caption is going to be friendly, with a call for them to “share a story” or “tag a friend.” On the other hand, if you're looking to promote a product, service, or contest, you're going to need a stronger call to action. (See below)
I've put together a list of four things to keep in mind while crafting your caption.