Room Tones and Wilds
Collect room tones. This is recording the sound of the empty set. You should try to record room tones for every angle from which you shot. So when you have finished shooting from one angle collect 90 seconds of room tone.
Dialog wilds are recording the dialog close up off camera. The talent is still in character and still in "rhythm". Do at least four takes of each line. This could save you from having to do ADR sessions.
Set wilds are recordings of sounds that emanate from the set. This includes doors, furniture, squeaky floorboards, tableware, sinks, toilets, cars (engines, doors, pull-outs, pull-ups, starts, stops, start-ups, etc.), elevators, ambiences and crowd Walla. For crowd Walla you can just roll for several minutes before you ask for quiet and begin shooting, it sounds much more natural.
These things will take some extra time on the set but will be worth your while when you get to audio postproduction.