Inhale while applying a flame to the bowl, make sure theres some weed in it too. Seriously thats about it, just hit it like any other smoking device really. I don't get how people can't hit a bong properly, I've never had a problem with it and haven't found it any different from any smoking device.

You should always inhale as much as you possible can when you smoke, I think a lot of people will stop when their lungs start to burn a little, which is why they aren't used to the smoke being so smooth from a bong and don't hit it as hard.