1. Pick a ski hill. Pretty much any ski hill will do.
2. Forget everything IMBA/Sierra Club/grumpy old people ever told you about sustainable trail building.
3. Tape off a 10 to 20 foot wide swathe that goes mostly down the fall line, with some turns. Do not go around massive boulder fields. Maybe criss cross some clear cuts, too.
4. Weedwack inside the tape.
It's a simple formula. Check the video for evidence:
Crystal Mountain, Washington. Approved by Kovarik, Voreis, Steve Peat, Shaums March, and Darrell Young.