You can look online for sample proposals that you can work from, in many cases you will be able to download a template that you can work from. You will most likely find that there are dozens of sites offering hundreds of different templates to download. It may take a while, but you will find that there proposal forms that will match almost any need including yours. Take your time and select the one that best suits your needs.
The other design factor aside from the text is the imagery that you can use. Many of the newsletter templates will come equipped with basic clip art or graphics. Others will include areas where you can paste in your own graphs, photographs, or other graphic items that help round out the information. It's important to remember that the first thing that people often look at, even before the headlines, are the images, so make sure that they are strong ones that are eye_catching. Color newsletters also tend to be more appealing than those in black and white, though they can cost a bit more to print.