You never can be too well prepared. That's why you should always carry a little piece of foam in your mic box. You never know when someone toting an upright bass is going to show up at your stage and you need to be ready if they don't have a pickup installed.
The trick is to grab a good old SM 57, double the cable back up the side of the mic (like all the kids in the hardcore bands do), wrap the foam around it and jam it behind the bridge. Plenty of string sound, plenty of resonance. I once got a standing ovation from a stage crew at a festival for pulling this one out.
With the mic pointed straight up you can turn it up pretty far in the monitors which is something you're likely going to be asked to do. As long as you're careful about high passing your monitor sends or notching out the resonance of the instrument on the channel you should find you have plenty of gain before feedback. Just be careful you don't notch out too much or you wind up with a glorified acoustic guitar.
Tune in tomorrow Brethren of the Knob and Fader when we'll bring you more quick mic tricks. Send in your requests and we'll post em up.