[mind|watch] {one's} manners

to make sure to behave appropriately and politely

When you visit someone's home, it's important to mind your manners and show appreciation for their hospitality.
Parents often teach their children to watch their manners when dining in a restaurant to avoid disturbing other patrons.
During the job interview, it's essential to watch your manners and demonstrate professionalism and respect.
The etiquette coach emphasized the importance of minding your manners at formal events and gatherings.
Even in casual settings, it's a good practice to watch your manners and be considerate of those around you.