Paul, are you delivering these in areas that you already work in?
If so, why not tie your leaflet in with your van livery and uniform??
You will slowly start getting a better response with each leaflet drop if you follow this advice. Guaranteed!
It has taken me 3 years making my locals aware of our company through van livery, uniforms etc. These have always been kept the same style and colour.
Big companies (sky, bt, dominoes etc) spend millions on marketing advisors to help with brand awareness, so why shouldnt we try it in our own little way.
Also leaflet an area once a week for 2 months. Same leaflet in the same houses. Excellent results again and more compact work. DONT bang them all out in one go and expect good results.
Hope this is of some help.