Leaflets, like all forms of marketing, work sometimes but not all of the time. When I first started in 2008 the first leaflet drop I did, which I'm guessing was less than five hundred, resulted in 3 jobs. Easy I thought! I don't think I've reproduced that since. I've had leaflets delivered with newspapers at 10,000 a time, leaflets delivered by our local milkman at about 500 at a time and leaflets delivered by me at anything from 100 to 500 at a time all with varying degrees of success. What I've found though is that the design of the leaflet doesn't seem to be as important as the content. I've done two-sided glossy A5 and single-sided black and white paper leaflets and both have provided results. You've got to be realistic though and realise that most will be binned before they are read but some will be kept and you will get calls sometimes months after the leaflet was delivered. Like everything else you've got to keep at it and you'll end up with results.