Principles are principles, regardless of the era. The media may change from ink on paper to flashing photons on a screen but the fundamentals remain. That which is badly done in one medium is badly done in another.
Here are some tips on effective copy from a journal The Graphic Arts, published in 1915. I lifted a few quotes from an article titled “Conspicuous Features in Advertising.” by Henry Lewis Johnson. He writes about advertising when this meant print advertising, and print advertisement of that time seem dense and clumsy to our eyes. Nevertheless, the fundamentals remain.
Consider how these ideas apply even today to copy written for the web.
Write the way your readers talk:
The theory of straight talk is the theory of colloquial English. It is the rule of thumb that bids you talk in advertising, the same language the wise salesman speaks to his customer—forceful, direct, definite. In other words you use the words we speak rather than the words we write, and employ the vocabulary used in conversation
Once they find you, for goodness sake, give them something worth reading:
The element of surprise is almost wholly lacking in advertisement literature. Much display line text is clever about attracting attention, but it frequently happens that little remains to hold the attention when once it is gained, besides a bold statement of fact regarding the article advertised. Most advertisements read like stories where plots were given away in the introduction. After the first sentence, no novelty awaits the reader, no memory-haunting phrase, no deft comparison, no unexpected turn in the thought to induce the reader to keep on.
Be direct. Clarity trumps cleverness every time.
There should be no magic or mystery in this business of copywriting. If the advertisement writer would cultivate the faculty of direct appeal and the characteristics of brevity and simplicity, he would achieve half the secret of the craft. It is when he strives for effect, becomes forced instead of forcible, that he begins to flounder and unwittingly falls into a line of talk which is not understood…
Bottom line: weak copy reduces the chance that your reader will buy your stuff. They knew about that 100 years ago. That’s one fact that never changes.
The good news is that good copy, strong copy, compelling copy will trigger buyers to do their buying thing. It doesn’t get in the way — it makes buying easy.
If you have something to sell (and who doesn’t?), that’s worth the investment.