I'm not a pro but I do go to ballooning events at least once a year so this is based on personal experience:
Look around a lot, opportunities will present themselves every few seconds! Get the light behind you or side on like with most subjects so the light is flattering.
I find the crews working to inflate the balloons can be as interesting as the balloons actually in flight so take the time to check out what's going on down on the ground too.
I normally use exposure bracketing because the metering can be thrown out by bright balloons catching the sun etc, I tend to find the shot I want then get a burst, at least 3 shots because the balloons in flight are always moving in relation to each other and often are only in the most pleasing formation for a split second so this will help to get the perfect balance. Don't go overboard and just point the camera anywhere and takes 0000's of shots though, defiantly search out and compose the shot first then take a burst just so you can make the most of each composition.
I also tend to take bursts when I use tele lenses just as a rule, memory is cheap and I'd rather pop off three shots and get a sharp one than go home and find that one awesome shot is ruined by camera shake, again don't just take photos aimlessly but get a shot composed then take a burst, just to give yourself a little breathing space back home.
If you're not shooting raw and it's nice and sunny set the white balance to daylight or about 5500k, if you leave it on auto the chances are the camera will neutralise the beautiful glow of early morning and evening light. Artificial colour casts are bad but natural ones are not!
Shoot whole balloons by all means but also zoom in on distinct parts, don't be afraid to go a little abstract, these things really catch the light in the most interesting ways so don't be afraid to close in on specific parts if you think it will make a good photo.
I hope some of this is helpful!