Crawfish boil help

Grill your sausage. The grease from the sausage makes the crawfish taste crappy and makes your leftovers all taste rancid.
I would disagree. Some people like adding vegetable oil to make the peeling easier. I don't do that, but adding the sausage accomplishes that goal.

Also, mushrooms do great in a boil. I add them a few minutes before cutting the flame. Warning: you can't put enough mushrooms in there and they will become the most popular item of your boil.

Also, I like to use a lot of celery salt.