Crews are the lifeblood of a production.
Treat your crew poorly, the movie wilts - and could potentially die.
But treat your crew well and you'll actually maximize the monetary value of your movie.
Buy everybody a great lunch.
Show gratitude on an individual level.
Treat everyone kindly, including the "lowest" member in the totempole.
Follow-up on everybody with thank yous.
This kind of incentivization doesn't really cost anything, and what you will get in return is a crew willing to do whatever you say with the full force of their creative and laborious spirits.
This love turns into production values visible on-screen.
So your movie will look & sound better simply because you were nice to others.