Pick a suitable workspace that can handle some permanent damages. You need a space that's both large and well ventilated.
Working outside is a plus when it comes to ventilation, but an indoor facility with 3 perfectly placed fluorescent lights will show flaws in your shaping so you can catch them early on.
This is a weather dependent project if you work outdoors. Know that you won't be able to do any work in the rain, snow, or even in the wind.
It may be a good idea to build a room specifically for board building; for a short board you will need at least a 10 feet x 8 feet (3 meters x 5.4 meters) room and longer than 10 feet if you're building a long board.