Last Friday, the theatre critic Mark Shenton was distracted from a five-hour performance of Philip Glass's opera Einstein on the Beach by a woman in his row taking photographs with a flash. It turned out to be Bianca Jagger. She had been snapping in defiance, Shenton claims, of complaints from those around her. Jagger has since said that others were taking pictures, too, adding that Shenton insulted and assaulted her. (He denies the latter, but admits the former with some pride.) The rules of behaviour in today's theatre audiences certainly seem to have changed. So, in the spirit of public service, and after consultation with Guardian critics, here is a new code of conduct.

1 Don't rattle your jewellery

All noise matters when you've come to listen to something. So a rustling packet in a classical concert can be as distracting as someone walking in front of a cinema screen. This makes even minor noises problematic. Vibrating phones are one example (we'll get to ringing). Vigorous page-turning is another. (In German concert halls, apparently, this is looked upon very gravely.)

Even jewellery is a common problem. "It's women who insist on wearing those multiple bangles," says our classical critic Andrew Clements, "so that every time they move their arms, which they invariably do in the quietest passages, you get extra unwanted percussion." Clements also complains about loud snoring, so if you know yourself to be a snorer, perhaps have a can of Red Bull before the show. The weak-bladdered should have half.

2 Do you really need an audioguide?

If you go to a gallery to be told what to look at, then by all means get one. But if you go along to explore, to be surprised, to linger around works that excite you, then all you have to do is, well, walk around. "Will an audioguide help you to get more?" asks art critic Jonathan Jones. "Or will it distract you from a fresh encounter with the art?"

Freedom of movement, he thinks, should be protected: stand where you like, look as long as you like, go back and look again. Anybody who objects can wait their turn. Freedom of speech, on the other hand, can be a nuisance. "What's annoying," says Jones, "is when someone loudly holds forth about a work, oblivious to strangers who are also looking. This can be distracting and destructive – even on the rare occasions when the showoff actually knows anything."

3 Talking, lateness, cameras, food, body odour

Michael Billington describes food as his "chief beef" in theatre audience etiquette, and recalls someone recently bringing a whole Chinese takeaway into The Duke of York's in London. Tim Ashley describes other people's body odour as his great bugbear, and insists other opera critics say the same. "If you're sitting next to somebody who stinks through six hours of Wagner, it can be a trial," he says. Theatre critic Lyn Gardner, meanwhile, is of the firm opinion that "people's bladders have quite clearly got weaker over the last 20 years".

There are difficult choices here. Cinemas and regional theatres often rely on confectionary sales to survive, so they do end up contributing to the rustling menace. As for lateness, there is a feeling that some venues could be far more sensitive about when they let the tardy in. After an overture is OK; between movements of a symphony is not. (Composers could start notating such moments in manuscripts, using whatever the Italian is for "latecomers".)

The principle, in short, is to avoid annoying people. So if you've annoyed somebody, you're in the wrong (and let's face it, you're never going to convince them otherwise). If somebody complains, obey them – and argue about it afterwards.

4 Your right to throw beer ends where my body begins

This observation from rock critic Caroline Sullivan is a reminder that, although gigs clearly have more relaxed rules than most other shows, there are still rules. And beer-flinging is certainly not permitted. "I experienced it most recently at Kings of Leon in Hyde Park," Sullivan says. "The entire audience expressed their enthusiasm by throwing pints over each other."

Accidental flinging also occurs, often as a consequence of lazy carrying. So if you're buying drinks for your friends, you are not allowed to transport more than three glasses at any time.

Sullivan does not object to mosh pits, though. "If you want to mosh, go down there and I'll stay at the back," she says. Her main grievance concerns her view. "Tall people really should play fair and stand at the back," she says. "I think it should be law." The practical considerations here – if a tall person has a short friend, or if he wants to mosh – have yet to be ironed out.

5 It's called "children's theatre" not "nursery"

Quite naturally, parents want to avoid spending time with their children. But the price of a ticket to a children's theatre show does not include babysitting services from those on stage.

This exercises Gardner, especially when parents look as if they know the rules but can't be bothered following them. "What they do is sit there while the show is going on, looking at their mobiles, and allowing their children to wander all over the stage," she says. By the same token, if you've taken young people to the theatre, and they are clearly bored, don't try to force them to be interested. This is unreasonable and counter-productive. "Not all theatre is good," says Gardner. "A lot of it is really rather dull."

6 Hecklers are allowed to say two unfunny things

Standup is unusual in that audiences are expected to try to spoil it. Many comedians disapprove of heckling and in bigger venues it's impractical; even so, people do sometimes shout funny things, and most comics will have a decent putdown ready if hecklers fail to reach a certain standard.

However, heckling is an art for miniaturists. If you think you've thought of something funny to say, but it doesn't get a laugh, then you need to revisit that assumption. Spoiling the performance in an attempt to save face is not the answer. Drunk people are very slow to learn this. At one Scott Capurro gig in Edinburgh, I remember a young woman having to be physically removed by staff because she would not stop interrupting (a surprise, because his audiences are often only too happy to walk out). Perhaps this punishment should be meted out more often.

7 Off means off

About 10 years ago, it became routine for venues to warn audiences to turn off their phones. About five years ago, everybody stopped noticing. This is a forgetfulness problem, in short, and it will never go away. (Phones also ring at funerals, remember.) Instead, we have to manage it. So when you turn your phone off, it should be off, not silent. This discourages you from distracting people, or yourself, with its vibrations or lights. It's tough but necessary. When staying connected is important, there could be limited exceptions. Gardner suggests that theatres should institute special rows of seats for tweeters (as happens in parts of the US).

Billington even recommends turning off your phone with time to spare. He cites the US director Bartlett Sher, who believes audiences need a while to disconnect themselves from all their everyday worries – perhaps 20 minutes. By the same rationale, you should always arrive early, as Ashley does.

8 Don't be so bloody precious

Overreacting is antisocial behaviour, too. So if somebody's annoying you, in any way, act early. Think carefully about what you hope to achieve, and – if you can achieve anything – speak kindly at an opportune moment. Don't just stew until your anger overflows.

In the theatre, where Gardner describes "a sort of war" between the old guard and the new, this is a growing problem. Star-led casting, in particular, brings in people who are not used to the environment. They are more liable to behave badly, but they are also badly needed. If you love the theatre, then you are doing it a disservice by sending them home annoyed. On the other hand, when something is being a distraction nearby, you have a duty to do something. Others further off may be equally annoyed, but powerless, so they are depending on you.

Remember that – and don't rely on having an enraged Mark Shenton at the end of every row.