I play guitar and usually I just pluck the notes on the third string one by one going up and down. WHen You hit the note that is the key of the song you will know that it is right,it just seems so. Sometimes I can get a bit mixed up as the firth of the scale will have a lot of tone in common with the root, usually takes me less than 10 secs to get the key of a song on my guitar just by using the above method and I have a bad ear for knowing intervals that kind of thing, but finding the key is not that difficult usually.

The above method will work for backing a singer too, just tell them to start singing and go up your third string of guitar until you find note that tonal wise fits in with what they are singing(will work on other instruments as well as paino)

joe


joe