Don’t trap them. Figuratively or literally, such as 30,000 feet in the air, in a plane.
Do give them an out so they’re not pressured to say yes in the moment…only to go back on it later. Hey, we’re sure he or she will say yes! But juuuuust in case, maybe don’t propose when their only escape option if they say no is jumping out of plane. (Spoiler alert: the woman in this video says yes…but who wants to say no to someone they’re about to spend hours on a plane with?)