to keep one’s figure

Keep your eyes peeled!

to keep on

to keep the golden mean

to keep one’s hair on

to keep dark

to keep one’s hair/shirt on

Keep your powder dry!

to keep in check

to keep one’s head

to keep one’s hand in

to keep one’s hands off something

to keep one’s head above water

to keep one’s head below the parapet

Keep your seats!

Keep your pearls of wisdom to yourself

to keep one’s lines of retreat open

to keep one’s mind on something

to keep one’s mouth shut tight

to keep one’s nerve

to keep one’s nose clean

to keep one’s nose out

to keep one’s promise

Keep your hands on the wheel!

to keep one’s shape