What kind of extension cord should I use for woodworking, and how should I place it?

Use a GFCI extension cord and keep it off the floor. GFCI prevents shock by shutting off power if electricity leaks, and off-the-floor placement prevents sawdust ignition since sawdust is fuel. Use 12-gauge for heavy tools, 14-gauge for lights, never daisy-chain, and inspect cords before every use.