I use a capo for different reasons. Its a quick and easy way to transpose a song into a differnt key. Then there are other songs that (to me anyway) sound a bit sweeter with a capo, like Ashoken Farewell. Also, when I play some faster flatpicking reels, I capo up, maybe to the fifth because its easier to play....frets are a bit closer and its right in front of you. Also, when I am jaming with others, I'll capo up to add a bit of mandolin flavor to a song. On top of that, sometimes my singing just doesnt fit on the lower frets, so....capo it up a few to where I can hit the notes. Just experiment. There arent any rules. Keep what you like and ditch what you dont.