1. Don't give a frame of reference.
A short person only really looks short when you see them next to other, average sized people - or things which have a familiar height (doors, for example).
Tom Cruise rarely looks short in his films, but at the same he's not constantly shown in "funny camera angles" (wide angle, shot from below etc). He just isn't generally placed right next to tall people.
A very slim person will tend to look tall with no frame of reference just because the only cues to height you have are their own body proportions. This is the case with supermodels who are not particularly tall, but look like they are in studio photos.
Sometimes the use of camera angles (manipulating perspective) to make someone look taller can backfire, since the effect may be obvious and draw attention to itself when the subject's height may not otherwise have been noticeable.
2. Distort the frame of reference.
Hire a bunch of even shorter people to appear with the person. They will seem tall.
This trick is used a fair bit in films - think Lord of the Rings. They hired some very tall actors, some actors with very large hands, some on stilts and more, to make the hobbits look small when they go into the inn. Opposite with Gandalf. The actor's just not that tall, but they used some very short stand-ins for when you see Bilbo, the Hobbits etc with the back of their heads to you. Likewise they did this with over/under-sized set design/props too.