Simple and to the point works best. Imagine that as the person is walking to their door, they see your flyer. From the moment they see your flyer until the moment they reach it, they are absorbing the information. Most everyone's first inclination is to crumple the flyer up and throw it away. So you have that small window of time to make an impression, and convince them to change their minds. Keep that in mind as you are creating you flyer. Large bold important text. Good use of white space. They need to know what you do and what you're offering in a split second. Once again, another flyer thread, and everyone seems to be under the impression that 400 flyers is a lot. You should do a minimum of 5,000 flyers, either yourself, or through a flyer distribution company, before you can know whether they will work for you.
What ever your angle or deal is (most important), business name, catch phrase, phone number, what it is you do, why you're special, and whatever else you think will get their attention.