I worked with an SLP on D and T (a voiceless D) for a very long time because I really struggled with those sounds. We focused on controlling the tongue and giving very light contact on the roof of the mouth. I did a lot of practicing, but I struggle way less on those sounds ( not that I never stutter on them but not the severe blocks or the frequency of them). And this was 8-10 years ago so there has been carry over ever since.