I've always had a copy of The Economist Style Guide close to hand - of course, I can't swear I've always abided by its rules - but it has been a valuable aid when people question why you've written something in a particular way.
I should therefore have guessed it would be online - and sure enough, it is (albeit a condensed version). I commend it to all right thinking PR and marketing people. The following section on use of jargon is particularly helpful:
Avoid it. You may have to think harder if you are not to use jargon, but you can still be precise. Technical terms should be used in their proper context; do not use them out of it. In many instances simple words can do the job of exponential (try fast), interface (frontier or border) and so on. If you find yourself tempted to write about affirmative action or corporate governance, you will have to explain what it is; with luck, you will then not have to use the actual expression.
Avoid, above all, the kind of jargon that tries either to dignify nonsense with seriousness (The appointee...should have a proven track record of operating at a senior level within a multi-site international business, preferably within a service- or brand-oriented environment, declared an advertisement for a financial controller for The Economist Group) or to obscure the truth (We shall not launch the ground offensive until we have attrited the Republican Guard to the point when they no longer have an effective offensive capacity — the Pentagon's way of saying that the allies would not fight on the ground until they had killed so many Iraqis that the others would not attack).
What was meant by the Israeli defence ministry when it issued the following press release remains unclear: The United States and Israel now possess the capability to conduct real-time simulations with man in the loop for full-scale theatre missile defence architectures for the Middle East.
Try not to use foreign words and phrases unless there is no English alternative, which is unusual (so a year or per year, not per annum; a person or per person, not per capita; beyond one's authority, not ultra vires; and so on).