Total cleanhouse of all coaches, trainers, management, anyone associated with the Lions over the last 10 years.
I then copy what Jimmy did in 1989 by trading what few quality players are on the roster. The Lions already started this process by trading Roy Williams to Dallas for some picks. I would try to put another couple of trades like this together.
As for a new coaching staff, I would try and get somebody like Dick Lebeau, a disciplinarian known for always producing solid defenses. He then can hire whomever he wants for a staff.
I would also emulate Jimmy in another way in 1989... the unsigned player revolving door. Sift through every player released by other teams on a weekly basis. There will always be some diamonds in the rough (or poo poo if you are Emmitt Smith).
Draft philosophy would start with building an offensive line and defensive line. I am a firm beleiver that football is won on the line of scrimmage, and whoever controls it best is most likely to win. After this you can start grabbing other positions like QB, safety, MLB, etc.