I also have a small notebook. I take notes on some jobs about technical questions or observations. And it’s really handy if I need to remember to change a take name etc. when there’s time later in the day.
I always have a large section of Velcro – a piece of both the hard and soft sides. This is so I can attach the timecode box or a Comtek for a scratch track to the camera (if the Camera guys allow me to put them on their cameras!).
If they don’t want Velcro, I use Bongo Ties to secure such things to the camera.
For successfully securing lavalier microphones to talent I have several things in my bag.
I carry Moleskin in both peach and black colors depending on talent and their wardrobe.