I started playing coffee houses in 1966. Then, they were like bars for kids, a place with no liquor where teenagers and college students could hear live music.
We'd play two forty five minute sets back then. But back then, I'd sit in my bedroom and play and sing for six hours or more, every day. That was my tv and my video games combined. I never even thought it was "practicing." In the summer I couldn't wait to get up and play.
If you are interested in gigs where they want you to play more than two forty five's, long the industry standard, then you need to practice. Even if you aren't, you need to practice. Most people practice riffs and going over the same song, it's a great idea to practice doing 45 minute sets, singing each song all the way through without stopping for mistakes. You might find you already have 3 sets ready (most people think they need more songs to fill an hour than they really do.) Practicing like this is often called "rehearsing."
Now, just wait until you're doing dance gigs. On the weekends, we play the first set for two hours non-stop, take a half hour break, then play for another non-stop hour. At the bars in Chicago, when I was young and foolish, we'd start at 9pm and play until 4am. Of course we'd take long breaks. I'm not telling tales here of walking through the snow 5 miles to school, just letting you know that it can be done.
A little comedy doesn't hurt. Go online and collect a bunch of one-liners and a few long jokes. I used to tell one joke (a long thing with a tongue-twister that is over a hundred years old) that I used to get requests for. They're great when you break a string.
Great that you're doing this, coffee shops can be a lot of fun...the audience is sober and wide awake.
All the Best,
Mike
------------------
You have to practice improvisation. -Art Tatum
Mike Dunbar Music [This message has been edited by Mike Dunbar (edited 06-28-2006).]