Some enjoyable rules from Guardian writer Tim Radford's "25 Commandments for Journalists":
* No one will ever complain because you have made something too easy to understand.
* The classic error in journalism is to overestimate what the reader knows and underestimate the reader's intellegence.
* Metaphors are great. Just don't choose loopy metaphors, and never, never mix them. Subs on the Guardian used to have a special Muzzled Piranha Award, a kind of Oscar of incompetence, handed to an industrial relations reporter who warned the world that the Trades Union Congress wildcats were lurking in the undergrowth, ready to dart out like piranhas, unless they were muzzled. George Orwell reports on the case of an MP who claimed that the jackbooted fascist octopus had sung its swansong.
* People will always respond to something close to them. Concerned citizens of south London should care more about economic reform in Surinam than about Millwall's fate on Saturday, but mostly they don't. Accept it. On 24 November 1963, the Hull Daily Mail sent me in search of a Hull angle on the assassination of President Kennedy. Once I had found a line that began "Hull citizens were in mourning today as..." we could get on with reporting what happened in Dallas.
* Beware of all definitives. The last horse trough in Surrey will turn out not even to be the last horse trough in Godalming. There will almost always be someone who turns out to be bigger, faster, older, earlier, richer or more nauseating than the candidate to whom you have just awarded a superlative. Save yourself the bother: "One of the first..." will usually save the moment. If not, then at least qualify it: "According to the Guinness Book of Records..."The Sunday Times Rich List..." and so on.
* There are things that good taste and the law will simply not let you say in print. My current favorites are "Murder acquitted" and (in a report of an Easter religious play) "Paul Myers, who played Jesus Christ, emerged as the star of the show." Try and work out which one has the taste problem, and which one will cost you approximately half a million per word.