In his classic book Think & Grow Rich, Napoleon Hill says that one of the major causes of failure is that people “prefer to act on opinions created by guesswork or snap-judgments rather than facts.”

How does this apply to advertising? Think about it: Almost all businesses haphazardly run whatever advertisements seem to be “pulling well lately.” In other words, advertising decisions are based on what the owner thinks will work rather than what the marketplace actually wants.

TEST IT Get away from guesswork by putting every important marketing and advertising question to a vote by the people whose ballots count: customers and prospects.

This voting takes place in the form of small, inexpensive tests. An advertising test is different from a questionnaire, a survey, or a focus group, and it allows you to definitively find out which headlines, offers, prices, etc., the market will respond to. You'll know what will cause prospects to buy before you spend a fortune on advertising.

Ultimately, the purpose of testing is to demand maximum performance from every marketing and advertising dollar you spend. You will find that one approach will often substantially out-perform certain others.

NO GUESS WORK You might think this sounds so obvious that everyone must be doing it.

Are you doing it? Just running an ad and saying, “Dang, it! That didn't work!” doesn't count.

If you methodically test and calculate your advertising efforts, you will shred your competitors' advertising to pieces and attract their customers.

Every aspect of your advertising can and should be tested — advertising mediums, placements, headlines, prices, offers, formats, typefaces, sales pitches. Everything.

If an advertisement or promotion fails in a small-scale test, either adjust it and test again, or scrap it for something different. That way, it's science, not conjecture.

—Rich Harshaw, author of Monopolize Your Marketplace, is a marketing expert;