Have several people read them for spelling mistakes and factual errors. A leaflet is usually shorter than a pamphlet, but both can be used for canvassing or information tables. Again make sure they are readable. Newsletters - A newsletter is an expanded form of a pamphlet. It can contain more information but should follow the same guidelines of readability.
Newsletters are probably better than pamphlets for mass distribution.
However because they contain a lot of information and may involve several issues, make sure you have sufficient resources to put one out. On the other hand if you see your role as providing information and alternative views, a newsletter maybe just the thing for you. Basically it consists of portraying your message in a theatrical visual fashion. You do not have to be a professional actor to do this and probably should not be. Popular theatre is useful because it can convey images and emotions that speeches or written material cannot.