When doing aquatint, at Cascada Studio, as a student, I tend to ask, that you proof the plate in between all the various tones, this is quite cumbersome, but done for a couple of reasons:
1) If new to aquatint, you get to see the print "build up"
2) You get to apply the aquatint more than just once
3) You get to proof the plate, as in using the press, inking up, wetting
paper etc, all to go in your little mental logbook for later, when you come to the editioning.
When we degrease the plate the first time, I use pumice powder, quick and clean and environmentally safe.
For subsequent degreasing, I brought back a tips from Asia, I use soy sauce, that's right, I apply a coat of soy sauce to the plate with a soft sponge and work it in, this is a super gentle way of degreasing,