Stop using Twitter DMs for marketing or publicizing your stuff. Just. Stop. (You’re going to like this one. It’s short to read and I am telling you to do less.)
A minimum of 90% of the DMs I receive parrot the exact same stuff/links that is already on the sender’s Twitter profile or in a bunch of their tweets. If someone’s already looked at your profile and decided to add you, you don’t need to repeat yourself in a DM.
“But I’ve got free stuff to share with followers! I need to make sure they don’t miss it!” Tweet it instead. Twitter is for tweeting. You can add it to your profile, too. It won’t be that hard to find. Honest.
And really, if you’re tweeting it AND DMing it AND it’s also on your profile, how do you think you look to people? Not like a real person interested in connecting or being social on social media. You come off as spammy to most people. (Really. See my survey results from last year about this topic.)
Remember that a DM is a personal contact, and when you use it for advertising, it’s completely impersonal and it’s broadcasting instead of being social/communicating.
So what’s the theme here? Once again it comes down to using social media to be social. Share your business stuff/creative stuff, sure. I do it, too. But you should also talk to people, meet people, share other people’s stuff you think is cool, occasionally talk about your spouse or kids, etc. Be real. Be genuine. Be an integrated human being. Be social.
TL;DR: Stop DMing your promo stuff. There’s almost never a good reason for it. Send your promos in your tweets or in your profile info. Not in DMs. Or any other private message for that matter. You are not special and different. Trust me.