You don't, really, it's in your genetic makeup- once you're done growing that's it.
P.S. Sleeping doesn't necessarily help. You grow the most in your sleep (hence why babies sleep all the time) but it doesn't (exactly) make you taller. Now every night when you sleep you "grow" a bit taller, but once you're vertically affected by gravity (when you wake up) you "shrink" again.
You will find you are taller in the morning then after a long day on your feet because gravity compresses the discs in your spine making you shorter. But it's minimal and really nothing you can do about it. Your height is what it is learn to love it.
Its a matter of genetics how tall you will be. The only thing that will affect it is treatment with Human Growth Hormone. You have to get that from a doctor, and they won't give it to you without a blood test to prove that you are actually deficient in it. If a person with normal amounts would take HGH, you would grow faster briefly, but stop sooner and in the end not be as tall as you would have been naturally. SO, unless you are deficient in HGH (which only blood tests can determine), it's just genetics. You can be sure that you have good posture; some people who feel they are too short are so embarrassed that they sort of "shrink into themselves" to be less noticed, and end up looking even shorter.