The best advice I can give is don't use the traps. Find a creek and get a friend and a seine net - you can catch as many as you want.

Instructions on how to build one: http://www.ehow.com/how_4671634_make...ish-traps.html

Cut the top off a 2 liter bottle, puts rocks in the bottom of the bottle, bait the trap, duct tape the top back on reverse, so the top of the bottle is pointing to the bottom of the bottle, put it in the water laying on its side.

Cut a 2-3 inch hole in the platic top of a coffee can. Place bait in can. Replace top. Place can in water, making sure the top is several inches underwater and build a bridge to the top with stones and rocks so that the crawdads can make it to the hole in the top.

Use a minnow trap.

http://www.ehow.com/how_2072181_crawfish-trap.html