Quote Originally Posted by kib View Post
I suppose just pronounce t and d more intenensively.
Also remember that in English, the "t" and "d" are alveolar -- they shouldn't be too "dental" or too "palatal."

And the classic exercise for practicing "aspiration" is to put a burning candle in front of your mouth, and try to make the flame move as much as possible while saying the English consonants "t", "d", "p", "b", and so forth.