I cut mine with a hot solder iron, I keeps the edges from unraveling. Then use a piece of heat shrink on each end to keep it in place.
My favorite style is the carbon fiber. I bought a few rolls of each size, along with a few meters of each size of black heat shrink tubing, and a multi-pack of colored heat shrink, from Parts Express and Mouser/Digikey.
I'll post some pics if I can remember.
2011 MINI Cooper S :: [build log]
HAT L6SE, L3SE, L1 Pro R2. 4x Alpine SWR-843D, JL XD700/5, XD500/3, Alpine H800, RUXC800, CDA-117
Re: TECHFLEX 101 A Comprehensive Look At This Product
When I did mine, I used black for current, white for signal, grey for speaker lines. But that was just to keep with the system's (and car's) colour scheme, as those were the only 3 colours used throughout).