To answer Mooh and the Pedant, at the place I used to work as an editor we used "practise" as a verb and "practice" as a noun. This was represented as Canadian usage (mid-Atlantic?). Exclusively with a "c" was regarded as British, and exclusively with an "s" was regarded as American. These were represented as tendencies, not hard-and-fast rules. However, I'm right and everybody else is wrong.

I practise as little as possible but take part in as many sessions and jams as possible; I find improvising with other players more valuable than rehashing old stuff. I never play anything the same way twice anyway. unless the tune is so strong that it refuses to be improvised upon.