Many people tongue too far back on the roof of their mouths. You want your tongue to be as far forward as you can get it without being on your teeth. 
Feel with your tongue on the roof of your mouth. There’s a knob that’s right in between the two front teeth. Then slide your tongue back along the roof of your mouth until you feel the ridge going up to the roof.
If you’re tonguing somewhere in between the knob and the ridge, your tongue is too far back. Tonguing that way slows you down. When you get to double-tonguing, it will create even bigger problems for you.
You want your tongue to be as far forward as you can get it without touching your teeth.
Sure, there are articulations later on that you might do between your lips, or between your teeth.
But in general, when you articulate a “tah” sound, your tongue should be as far forward as you can get it without touching your teeth.
So, if you feel that knob, that’s where you should be hitting.
It also might help for you to visualize that you’re making your tongue into a point as your articulate. This will help your “tah” to be very crisp sounding. And it will be a real help when you’re double-tonguing.
Lastly, if you can hear a noise when you tongue, that’s a sure sign that your tongue is too far back.
So, experiment with this and see if you can move your tongue forward. It will make a huge difference in your playing.
Let me know how this works for you.
Have Fun!
DoctorFlute
Watch me demonstrate this: FluteTips 1 Articulation Tonguing Too Far Back
Let’s Talk Articulation – Focus on Your Tah – FluteTips 179
FluteTips 4 Tonguing Problems – Noisy Tongue
Practice with Me Low Register Tonguing
FluteTips 47 Pizzicato Tonguing
