Don’t let BPD – Bad Package Design – ruin your mailing.
When the writing is done you are going to need an outstanding graphic artist with direct mail and print experience.
They can bring your package to life: make the envelope stand out in a bundle of mail; make your organization look exceptionally professional; make your letter easier to read and your reply card easier to fill out.
Don’t think it’s necessary? Too much of an expense?
Then you would be wrong.
We have conducted tests over the years where we split lists in half and each half received the same package but with different designs.
There was always one clear winner: often with a dramatic difference in response rates within each segment of the same list. Only the design differed.
After all, the design is like your calling card. If it stands out; if it makes a professional impression, people will respond accordingly.
Don’t skimp on design, It’s like scribbling your name and phone number on a piece of scrap paper and giving it to a potential donor. 
David