A practical tip for the blues harp player while on stage: Get yourself a Hohner "bandalero" harp belt. Either wear it or attach it to a mike stand, conga drum, etc. The belt has 7 slots for the major keys you will play, especially if you do Blues. When you buy a new harp, remove the key sticker from the case and attach it to the top right section of the harp. Now you will have your harps organized and clearly marked, even on a darkened stage, and will prevent those embarrassing upside-down and wrong key episodes.