Any change to one district impacts other districts. Every citizen gets to be in a legislative district however unpleasant it may be. However bad your new district looks, as an elected official, don't complain about your new district out loud. Keep in mind you might get sued. Document everything, and keep it.
Loose lips sink ships.
Use your attorneys. Must have competent mapping staff. As a legislator, be prepared to spend lots of time at the computer yourself. Be familiar with the data. Show colleagues on computers one at a time.