All good written communications are based on the same principles. Here's the top ten tips.
Why are you doing this? Write down in one sentence exactly what you want to achieve. Defining the purpose of your communication before you start will keep you on track when you start writing.
Most short communications focus on one or two key messages. Write them down before you start. This will help keep you on topic.
This is the most critical part of any communication. The better you understand the people you're writing for, the better you can target your message.
Get to know them really, really well. What do they think/feel/already know about your subject? What do they think is important? What role or job do they perform? What's their level of education? What do they do for fun? What do they read or watch? Where do they go and how? ...
The "environment" can include what your competitors are doing, the current economic or political climate, how a communication will be used, the context in which it will appear. Your environment might be a classroom, a workplace, the Yellow Pages, the local paper. Understanding it will influence how you get your message across.
A web page is different from a print brochure, true. But also take the time to think about how information appears physically. For example:
Use a mock-up of your medium to work out how things flow and when they appear. This will help you map out your communication.
Time spent planning your communication is time saved writing it. Don't stint on this step. Creating an outline of the structure lets you see how it will flow, whether anything's missing or whether some parts aren't needed. It's much easier to make structural changes before you lose sight of the structure in all the words.
Keep it simple and you keep it punchy. Fewer words doesn't mean your writing has to be dull, just choose those words very carefully. Then you have a better chance time-poor people will read them.
This is why you must get to know your audience. You'll write one way for a convention of rocket scientists, quite another for kids at a skate park, or people learning to use Word.
Spell the same words the same way. Punctuate your bulleted lists the same way. You don't notice consistency, but you certainly notice its absence. A "style sheet" listing terms you use commonly and how you want to spell them is a great help here.
Even a paper-based document needs navigation. Easy to navigate means easier to assimilate and more tempting to read.