I agree that a good part of it is trying not to stare and things like that. The answer is somewhere in betweeen. Don't stare too long, much like you would try

I agree that a good part of it is trying not to stare and things like that. The answer is somewhere in betweeen. Don't stare too long, much like you would try not to stare too long at a beautiful person. If you make eye contact, say hi. Don't kneel down, but instead make eye contact as you speak. Just like you would with someone quite a bit shorter than you - or the way you'd look up to a tall person when speaking. If the person seems to be struggling to reach something, simply ask if they'd like some help.