Originally Posted by: Jolly McJollysonThere are guidelines. Many, many guidelines. Pick up a good theory book on modulation and learn a few (if you plan on doing this with a band, have them learn the guidelines as well). I wouldn't say two keys work "best" together... Really you can modulate to any key from any other key. Though for quick modulations, the relative major/minor, the dominant, and the parallel major/minor are pretty simple.
Much thanks,
