There's a video at Rachel's English you might find pretty helpful.
Student or Learner
Can anyone tell me the tongue position of /t/ sound when it comes as a stop at the end of words?
I tried to raise the tongue as if I am going to say a true /t/ and stop before the tongue touches anywhere, but it sounded too much unpleasent and something different than what native speakers say.
I also tried to raise the tongue as I am going to say a true /t/ and quickly close the vocal folds but it sounds a hard glottal stop.
There're three videos related to this topic on Youtube by JenniferESL.
YouTube - Lesson 13a - True T and Flap T - English Pronunciation
YouTube - Lesson 13b - True T and Flap T - English Pronunciation
YouTube - Lesson 13c - True T and Flap T - English Pronunciation
Here is a tip about production of /t/ at the end of a word: you should release it like an inaudible release. There is a different between unreleased stops and inaudible releases. This tip works with /p/, /t/, /k/. Many voice trainers teach this.