At the beginning cutting out the windows and inserts I just cut everything with a sharp scalpel,....but now when removing engine deck details, I cut away as much was I can with side-snips,...then remove the rest with scalpel,....to get all surfaces flat I sanded with different grades of paper finishing with fine wet & dry,.....wet the paper to get the plastic really smooth again.
If an area like a window frame gets all messy,....the plastic looks all furry,...give it a blast of adhesion aid,.....then you can put a thin layer of super-glue on it.....and you can work with that then.....sand smooth with wet emery paper
J