The extremes here suck. The performer who speaks never, and the performer who speaks too much. It depends on the venue and the crowd I suppose, but if you are ignored you can't talk them into hearing you. Cliches and parodies of same don't work, neither do "in" jokes. Brevity is all. I once saw a well-known Irish singer/songwriter turn his festival set into a standup comedy routine wherein he not only spoke for most of his set but played covers of non-folk material when the crowd was obviously more interested in hearing him sing his own stuff. The lesson I think is not to be mislead by laughter, it doesn't necessarily mean the crowd is getting what they want, just that they're amused.I do want to know something of the song or writer or singer or its era or a quick related joke, I just don't want to hear too much information when I could be hearing music. Sometimes a few words say alot, I guess it's a matter of choosing the words.
There are no rules outside of forethought and common sense and that includes reading and understanding the crowd. The exception is the crowd that can't be read, which probably means alot of them don't want to be in attendance anyway, meaning "here goes nothing" is the order of the day.
Peace, Mooh.