1. Put your shoulders back.
If you don't slouch, you'll automatically gain about two inches toward your goal height. This is the best method I've found for tricking people into thinking you're a little bit taller than you actually are. People aren't used to others feeling strong and confident.
2. Always make eye contact.
Don't ever look at a person's chin when you're talking to them; make sure you look at their eyes. People of the same height make direct eye contact, so if you do too then you appear to be their height.
3. Take a step back when talking to a very tall person.
If you take about one step back while talking to somebody taller than you, it's easier to make sure somebody isn't looking directly down at you.
4. Never comment that somebody is taller.
Don't EVER accept that somebody is much taller than you. Stay in very strict denial and ESPECIALLY don't tell somebody that they're taller.
5. Put on a pair of heels if you're feeling brave.
Ladies and gentlemen, if you're willing to deal the blisters and crippling foot pain every single day, I'd say this is your best bet. Strap on a pair of heels and physically get five inches taller.
6. Don't admit you're shorter than people think you are.
If somebody thinks you're taller than you actually are and they say something along the lines of, "You're about 5ft 10, right?" And you're actually 5ft 6 (This actually happened to me) then you should just laugh and deny nothing. You don't have to lie, but you certainly don't have to correct them either.
7. Don't let vertically gifted people lean on you.
NEVER let those extremely tall and annoying people do that thing were they act like they're leaning against a wall, but they actually use your head as their base. You are not a wall. You are a person. Expect to be treated like a human being.
8. Most importantly, be confident and embrace your height.
If you embrace your height and who you are as a human being, you appear more confident. Isn't all of this really about confidence anyway? If you're happy at your height then ignore all of my tips and take the world by storm.