'Being a playwright of any race is difficult, and Lord knows it gets more difficult the further you get from the middle of the road.'-- Suzan-Lori Parks
The type style [the type face or font] should be an ordinary serif face: type that has those little feet-and-hand-like things at the ends of letters. It's the sort of type used by most newspapers and magazines like Time. It's much easier to read than the more "modern" looking sans-serifs.
And avoid italic type like it was the plague -- which it is. Italic type is very hard on the eyes when it's used for more than occasional word emphasis. Line upon line of it is enough to make the average reader of play manuscripts chuck the whole thing in the waste basket.
The Seminar manuscript format Example Pages use a so-called "typewriter fixed font" style, mostly to distinguish them from the rest of the pages in this Web site. With nearly universal use of computers and word-processing programs today, most playwrights haven't seen a typewriter in years. So they set their programs for some standard "proportional font."
Some common fonts for the job and that you can find in word processing
http://www.vcu.edu/arts/playwriting/