This article is full of supposed "secrets" that most everyone knows about flying. But one thing it mentions is:
14. Tipping could go a long way.
My girlfriend is a flight attendant. NO ONE tips flight attendants. If you give your FA a fiver with your first drink you’ll probably drink for free the rest of the flight.
Is tipping a flight attendant acceptable? Is it even permitted? (I know many businesses won't accept tips in the US, for instance, to avoid the legal obligation to report tip income to the IRS.)
BTW, flight attendants do not accept cash on board - only credit cards
-- For tips? Or for purchases? Many accept cash for purchases. Some accept only cash. It depends on the airline.