The best way to improve what you say, to make sure that what you say will come “true” is to honor your word.

There’s no shortcut for this, and honoring your word is very much a way to respect yourself and the people around you.
If you say that you’ll help your friend cleaning up the garden but then you don’t show up, how good is that?
Not good, right?
That’s respect, and it starts with the simplest thing, honoring the words you say.

James Altucher takes it even further, by trying to say only a precise number of words in a day.
This force him to evaluate anything he says so that the words aren’t wasted.

It’s a nice way to solve the problem, but you can also you the simplest route: do what you say, every time, everywhere, no exception.