I haven't been there in a long time; and when I was there it was not as a DoP. I will say the most basic rule when working in countries, anywhere, is be respectful, be yourself, be friendly, be willing to listen, and just don't do anything stupid.
Really rather jealous though-- I'd love to get back to central asia for some filming, it's a beautiful beautiful part of the world
Also be prepared to have to bribe people. Make sure you have all your customs documentation in order, and I would generally recommend making sure you let everyone know where you're going when- - you're still pretty far form the boarders, but, it's a whole new world.