The most important thing is mindset. Take responsibility for your own safety and be ready to handle the possible threats.
Next in importance is situational awareness. Walk around the unsafe holes in the ceiling. Move the boxes blocking the fire exit. Know where the exits are and how to get to them. Know what sounds are normal and who belongs where, if that's possible in your workplace.
After situational awareness comes planning. This can be simple: if the fire alarm goes off, I will move directly to the nearest exit and then to the fire assembly area. If I see a fire and it's small enough to fight it with a fire extinguisher, I will get the fire extinguisher that I noticed because I was paying attention and rock out my Pull Aim Squeeze Sweep. If the fire extinguisher doesn't get the job done I will drop it and run away screaming like a little girl.
Last and least comes gear. That's not a scold directed at anyone in this thread, as far as I can tell BPJ and all the contributors have mindset, situational awareness and planning nailed.
Having been through a wide variety of unpleasant experiences in office buildings, here are the things that I keep on my person:
- Cell phone
- If I drove, car keys
- Flashlight
- Locking folder
- Wallet (including a useful amount of cash)
- A keyring multitool and backup flashlight
- Pistol and spare magazine (where legal to carry)
Cell phone is obvious -- all I do differently is never let it get beyond arm's reach. Car keys can be very helpful if the fire alarm goes off and it's 10 below, or I need something from my car kit. The flashlight has saved my bacon too many times in basements, datacenters, construction sites, bathrooms with malfunctioning motion sensor lights and underground labyrinths of gigantic hospital complexes for me to consider not carrying it. The spare one on my keychain once allowed me to leave my oldest daughter in the designated tornado shelter without her having a panic attack while I went to collect the rest of my recombinant DNA. As we've mentioned previously cash is a great problem solver. While the keychain multi isn't much, there have been times it's been just enough better than nothing to solve small problems quickly.