I've read the posts here about tongue position when tonguing but I guess I'm missing something. For me at least, the only natural placement seems to be the tip of my tongue touching between the lips, almost like a stopper stopping them from vibrating. But the sound sounds like you'd expect, kinda blop blop instead of crisp and clean. So on the one hand I think maybe I just need to practice more. On the other I think maybe I need to just hunker down and practice not touching the lips, but the spot between teeth and gums on top, which is very unnatural and cramped. Thoughts?