Put on your breathing mask and open all the windows and turn on a couple of large fans. This will help circulate air in the room and blow out excess dust. Also, it will create ventilation to help you not breathe as much dust in as you clean.
Sweep as much dust from the floor as you can with a broom. Get the broom into corners as best you can and use the broom to brush dust off of window sills or ceiling corners.
Vacuum up any dust that still remains with a shop vac, then use a damp sponge mop to go over the floors to ensure all the dust has been picked up.
Run a damp rag over the walls to pick up any fine dust that may have been missed during the cleaning.