The Balinese are inclusive by nature and take great pride in their heritage and therefore do not mind visitors observing ceremonies and traditional dances, just as long as you follow a few simple, basic points of etiquette. (After all, how would you like a group of foreign speaking tourists invading your wedding or funeral of a close relative to snap a few photos?). First, dress appropriately - smart casual is appropriate - swim wear is not appropriate. Two, be quiet and respectful. Cameras and camcorders are ok - but do be unobtrusive.
Also do not step in front of anyone to snap a photo and do not sit higher than the local priest presiding over the ceremony. As well, Do Not touch or pat anyone (including children) on the head.
When visiting temples be aware that you should wear long pants or a sarong with a selendang tied around the waist (men and women). Whilst you can take your own every major temple has selendangs to borrow for a small donation. It is extremely bad form (in fact it’s taboo) for women who are menstruating to enter a temple.
Lastly a word about being stuck in traffic. If you do find yourself stuck in traffic for no apparent reason you may have come up on a Balinese procession on the way to temple. Be patient. No amount of honking the car's horn is going to speed things up and it's rude to try and pass.