Wear a hoodie, something to hide your face (but not completely obvious)
go to a different ATM each time you withdraw (no matter how far, you don't want to risk it)
cut card up and scatter around or just throw it somewhere in the garden once its empty
use a different shipping address to your actual house, a depot or something, maybe a house for sale that you can squat in.
that way trial and error is your best approach, if it works, well you've got money. If not you haven't given any valuable information.
Make sure to use a fake name when purchasing, and DoB, everything. you're not yourself.