Pressure to answer right now is often a sign you should wait.

Real emergencies are rare, and the urgency in most requests is manufactured, sometimes deliberately and sometimes because the other person wants to stop worrying about it. A decision made under artificial time pressure skips exactly the step where you would have spotted the problem. Anybody unwilling to let you think is telling you something about the offer. Speed benefits the person pushing far more often than it benefits you.

When you feel hurried, say you will answer tomorrow and see what happens. Genuine needs survive a night. If it is a purchase or a commitment, let somebody you trust hear the details first.