Start by wipeing everything down I used Auto carpet cleaner on everything the foam cleans the crevis very good and a shop vac
Next get some vent cleaner from the local auto parts store does a good job make sure you run the blower with the windows open for a good half hour after your done.
Bakeing soda in trays in the back seat for a week or so.
Good over all cleaning of all the seats and carpet.
Clean the ash tray out good and the area behing it.
leave windows cracked for a few weeks and a large portion of the smell will be gone.