There are many schools of thought on how to write a successful direct-response ad, letter or brochure. Some say you need to be subtle, some say be harsh, some say be round-about, some say be direct. There is one technique, though, that is coming to the forefront as one of the most successful to employ.
Info-Loading is the style of overloading an advertsement with information about your product or service. The theory is, you give the customer more information than they'd ever want on your product/service, and they'll feel more confident about you and what you offer. Also, the customer that actually reads through it all is the one who's interested enough to buy what you offer. The good news is, it works!
Here's how to do it. Say you're planning a quarter-page display ad in a magazine. Instead of leaving a lot of white space, so it looks open, and instead of putting pictures in to catch the eye, fill the whole space with text! Load it with as much information as you can fit in, without making it unreadable. To prevent it from looking like a grey blur when the reader's eyes scan through the page, put a bold, black box around the ad, a bold headline, and emphasize important words and phrases with bold print.
You can do the same thing with a mailing. Put together a four-page sales letter loaded with copy, then add a brochure/flyer that re-emphasizes the important points in even greater detail.
A few cautions with this technique. First, make sure you actually have something to say! We are so conditioned to being economical with our words in advertising that it'll be hard to info-load without feeling repetitious. Instead of rambling on about features, tell customers every single benefit they'll get from your product/service. BENEFIT is the important word.
Give Info-Loading a try. Depending on your audience and what you're trying to sell, you may find that info-loading can load more sales into your bank account!