I solo dive and don't like people touching my stuff. I'm not a fan of same ocean buddies, and rarely have any, so aside from my own predive checks, I don't worry about others.
If I have to be buddied up with somebody, then I'll point out my necklaced backup and 6' primary and go over hand signals for underwater communication, and since I always dive steel tanks, I let the other party know that I won't be ascending with them when it's their time to surface, since I'll have another 10 minutes or more left in my tank.