Now let's not have any confusion; I'm not suggesting that your next newsletter campaign should involve the painstaking construction of one email after another. No, I'm talking about the picture you have in your mind of who you are writing to, whenever you write.
Almost everything you write is for many people to read (if only in your dreams). You may have an email distribution list of 10,000 addresses or be hoping for 50,000 website hits; either way you will be imagining a healthy audience. Let's assume I'm reading an article you've written that contains the following statement:
This may well be true of the group you are communicating with, but that's not the point. What you have done is put me, the reader, in a crowd which is being addressed by the literary equivalent of a megaphone. You've made me feel like a punter at Hyde Park Corner listening to you warble on about your favourite topic. So if it's OK with you, I'm going to walk on; you've obviously got a big enough audience already.
If I hang around long enough, I might consider the point you are trying to make: that some of the readers of your piece don't recognise the need for quality writing. Are you trying to make me feel uncomfortable, an outsider in a self-satisfied group of know-it-alls? Well it's working, and I'm really going this time.
The alternative is simple: talk to one imaginary reader and do it directly and personally. Let your voice be inside her head, speaking to her privately. Not only will it be more effective but you will find your writing becomes more focused. You're showing that you are more interested in your reader than you are in listening to your own voice:
That's got my attention now. Whether or not you're right, you are talking to me and me alone. In return I'm going to give you the opportunity to finish what you want to tell me.
One thing to remember: if you have trouble getting a clear mental picture of your reader for a particular piece of writing, then face up to the possibility that you have too many segments of your market in mind. Pick one - your writing will benefit, and the message will resonate much more with your readers. That is exactly the effect you want to have; better the relevant words that make some people listen, than the general words that make everybody walk away.