A mute is pretty essential. As a free-folky (pocket) trumpeter (moved by the playing of Don Cherry) I use a Harmon / Wow mute (with and without the wow-tube) which 1) warms up the tone 2) doesn't piss the neighbours off, and 3) helps with the lower registers.

For examples check tracks 4 (Domus Terra) and 6 (Gospa Peregrinus...) at www.myspace.com/sedayne