For cheap seats in advance, I usually order through Broadway Box.
For a first time, I'd recommend Orchestra from E to about J. Ahead of E and you're so close that you end up couting sequins on costumes or playing Spot-The-Microphone. Behind J and you get under the mezz...which means you miss some things that take place above the stage.
Unless you really want to be under the chandelier when it rises and falls, front mezzanine is also excellent because you can see the "whole" picture.
Try to get the center of either, but avoid extreme right. Slightly to the left isn't bad at all.
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