You still won't be guaranteed success, but it will be a whole lot easier, if you follow these rules. 1) EXPLORE FREE AND LOW COST MARKETING OPPORTUNITIES. Too many people jump into mailing list a mail-order business with an expensive, flashy full-page ad in a big magazine. That's great IF it's successful, but what do you do when your ad only pulls enough orders to cover it's cost, and you have no marketing budget left for new ads?
Lick your wounds, and close down your business. The smart thing to do at the start (and throughout your mail-order career) is to take advantage of all the free and low cost marketing mailing list options at your fingertips. You say you don't know about any? Well, here are some ideas. Send a sample of your product along with a press release to the products reviewers at the magazines your customers read.
Also, write a short article about a subject or issue that will interest your potential customers and that has a connection to the product you sell, and submit it to those same magazines. For example, if you sell bass fishing lures, write an article mailing list on the best times of the day for bass fishing. Offer to talk about the subject on radio or TV talk shows regarding this subject.