Publicity should be factual and not criticise other institutions, according to a code of practice produced by the Secondary Heads Association. Schools are also advised to co-ordinate admissions procedures so heads know sooner how many pupils they are likely to have on roll during the coming year.
The code was drawn up in response to mounting concern over the aggressive marketing strategies used to attract pupils at 11 and retain them when they reach 16.
Colleges, in particular, have complained that schools with sixth forms do not always allow them full access to potential students.
According to the five-page code, publicity must be factual and relate only to the institution itself. There should be no explicit or implicit criticisms of other institutions.
"Advertising should not mislead and should maintain a degree of dignity in the interests of education in general," it says. "Highly selective and misleading quotations from inspection reports should be avoided."
It warns that the media may misrepresent exam results. If possible schools should agree a standard format, and raw exam scores should only be compared with previous years at the same school or with averages of reasonably large groups.
"We are all aware of the dangers of the market-led approach. If you start knocking other schools they will knock you back," says SHA vice-president Peter Miller, who helped produce the code.
If a pupil below the age of 16 asks to move, the school receiving the request should refer it back to the pupil's present school and only talk with the child's parents once it confirms that proper procedures have been followed. And donor schools should provide necessary information about the pupil to allow the transfer to be given proper consideration.
Pupils who have been offered places at more than one institution are one of the biggest problems heads face. If local schools agree to announce on the same date whether a child has been offered a place, SHA believes there is less chance of parents holding on to other offers and leaving schools uncertain how many places they have available.
Mr Miller, deputy head of Wrenn School in Wellingborough, says some careers officers have been accused of partiality in advising pupils about post-16 options. SHA recommends all education and training providers are invited to careers evenings and says that schools must be willing to distribute publicity material about colleges and other bodies.
But schools are advised not to release students' names and addresses to other organisations - the association says this would encourage bad practice and probably contravene the Data Protection Act. Only relevant incentives, such as books, stationery, bus-passes and childcare support, should be offered to potential sixth-formers, it says.
The code is expected to be discussed by association branches and, if necessary, adapted to local circumstances. Members who believe another school is not following the code are being told to contact the association's headquarters and, if the other school is led by a SHA member, it will be approached by SHA officers.
But the chances of punitive sanctions are small. "We don't have the power to tell members what they should do," admits Mr Miller. "I don't think we would discipline a person or ask them to leave the association unless what they had done was particularly bad."