keep your wits about you!

Keep your wits about you! (be ready to think quickly in a situation and react to things that you are not expecting to) — Не зевай! Не теряй головы! Держи себя в руках. (контекст.)

Example 1: (Benjamin, who graduated from a famous university in the East, asked Elaine out on a date). Elain's father:
I want to you to keep your wits about you tonight. You never know what tricks Ben picked up back there in the East (The Graduate)

Example 2: Give people the benefit of the doubt regarding their sincerity, but keep your wits about you; they might not be as truthful as they seem.

Example 3: I'm not takin' it lightly, Chloe. But we got a job to do here too, and this is no safer than a mountain under a bomb attack. You keep your wits about you, hear?

Example 4: Travelling in Moscow is potentially dangerous- you really have to keep your wits about you, and be one step ahead of the situation.

have your wits about you
If you can keep your wits about you while all others are losing theirs, and blaming you...