So I'm gonna attempt to save a few bucks buying my first projector online and setting it up myself.

Since projectors have both a minimum and maximum image size, I was wondering how I could tell what the "optimum" image size is, in other words, which image size for a particular projector will give me it's best picture, or is there even such a thing?

FYI, I'm looking for something that will display an 8 ft high picture.

Thanks in advance.