Can I 'DM' you?
Your customers will want to ask you questions on twitter but not all customers will want to publically @mention you.
And there are those questions, situations and issues where a public discussion is inappropriate.
This where the Direct Message (DM) comes inhandy.
Remember: You can only send a direct message to a person who follows you.
I'f you're a business that has lots of followers but you're not following them back you may missout on the opportunity for your fans to DM you a message. If they can't DM you they may not bother to ask you the question at all.
A good way to tell if this is an issue for you is to watch out for tweets like "Hey 'brand' can you follow back so I can DM you?"
With a DM you can easily send through an email address or phone number for the customer to contact you on instantly. It says "sure, lets get this sorted now, we can help". I'ts a very quick way to reduce discontent or the opportunity for the customer to vent their frustration publically.
Lastly Twitter is about a community. If you're being followed by many and are following few it could been seen that you are broadcasting more than you are engaging. It's about "being together" with your customers, sharing in whatever it is they want to chat about.