use the site Ian linked. Use the rate code that provides you the lowest duty while still being accurate. Part of the customs officer's job is to take incorrectly filled forms (declaring "used clothes" rather than "used garments, manufactured in Bangladesh") and translate what's there to what's in the tarrif schedule. If you do that work for them, it can pay off. They aren't going to spend ten minutes trying to save you a serious chunck of change.
For instance, if you sent a watch from the US and just labelled it "watch" you could be paying 35% duty. If you labelled it correctly, "automatic wristwatch, made in Japan" you'd get it duty free. The officer has no incentive to help you... That's why you must do your own research.
I find that actually sharing this information doesn't convince anyone. I stopped replying. Just let them lie on their forms and try sending it to their thai neighbors and have their family learn to write Thai script to save them nothing ...
Some smaller bars and clubs have found ways to be creative. You might just need to look a little harder. Bangkok never really stopped partying, it just went behind closed doors
they do a pretty good job too. Don't sleep on Thisrupt or some of the other new media that's sprouted up in the last few years. Some of the better coverage is in places you might not expect.