The best of the tricks to teach your parrot is to teach him/her to poop at a particular place. You have to be very careful and vigilant for that, as they usually give you 2-3 seconds time to react before they let go. Also 90% + times they poop right after coming out of the cage or change places after a while, so you can designate a place, a big bowl or anything and always take her there, right after getting her out of the cage, and say "Poop" or anything you would like to associate it with, don't let her go anywhere else before she is done.
When you become master of "catching the moment", tap that bowl or mat and repeatedly say "Poop", as an added measure initially, you can immediately take her to that area when you feel that she is about to poop.
Good Luck