With my vast experience of two swarm calls, this is what i do.
Have a cell phone on you - not in the car.
Take someone with you if at all possible.
Call someone at home when you are finished.
Take the time to do it right - A.K.A. don't get cocky.
Number one precaution - MAKE SURE YOU HAVE EVERYTHING YOU NEED BEFORE YOU GO!
(Always take duct tape)
I have decided I need a "Swarm Kit" that I can just pick up and go - at least for the small stuff.
I forgot stuff BOTH calls - felt like an idiot. I think on most calls you will have people watching - I had a bunch on the last call, in fact the homeowner asked to please wait 5 minutes to start because a lot of the neighbors wanted to come and watch. Turned into an opportunity to educate a lot of people about bees.
JC