[dredmorbius]

Why concede your adversary any advantage.

By calmly and clearly asserting your rights, you're preserving whatever slight edge you have. All the better if there are witnesses or recordings.

Allowing searches, answering questions, fleeing, or resisting, all work against you. Stating you don't assent, clarifying that requests are orders, and complying under protest, are options.

"Good (morning|day|evening) officer" is a good starting response. It makes clear that you aren't rattled, and concedes nothing.

And no, immigrants (or minorities) don't start with a fair break. But you can keep from letting that disadvantage erode further.

Slow movements, hands in sight, etc., all help.