I look at the safety card to see how the over-wing exits work: how to open it, whether the door comes off or hinges, and if it comes off, whether I'm supposed to put it on the seat or throw it outside (not sure what difference it makes but some cards say one and some the other).

Beyond the safety card...

If I'm in economy, I'll count the number of rows to the emergency exits.

I usually politely watch the safety demonstrations if the flight attendants are doing it live, thinking that if I was in their shoes I would appreciate it if someone looks like they're paying attention.

When they get to the part about life vests, I'll look or feel to make sure it's there and I know where it is.

And then I promptly forget everything I carefully noted. Oops. 🤷‍♂️