Facebook released some new policy changes to #Messenger (we'll cover soon) and along with it, they provided some best practices for the platform.
Respond Quickly & Set Expectations: Don't allow #unread messages to just sit there. Take time to respond and answer, if you don't have time to fully answer, let them know when they will hear back addressing their concern. Take advantage of the auto-reply feature, this will signal you've received the message and working on a complete reply.
Leverage: If they're in your #DM's, you have their attention. Don't go in for a sale or recommendation too soon but use the
open line of communication to send a targeted message down the road. Depending on how many messages you receive, this is a great indicator of you want to invest in #Sponsored Messenger Ads.
Short & Sweet: Address their concern and wrap it up with a bow. Messenger isn't the place to have full, in-depth conversations. If you feel compelled to extend the conversation, ensure their concern is addressed first.