Tools to Bring to an Installation

Double-sided Tape
Extra Batteries
Spare Wireless Router
Spare Ethernet Cable (in case they already have a router, and you need to plug in to it)
Spare Sensors
Spare Antennas (Z-Stick, etc.)
Spare Lamp Module (for Z-Wave installations)
Screwdrivers (including a small Phillips-head)
Flashlight
Power Strip with Surge Protector
Labels and Marker (for labeling sensors)
Hammer and Nails (in case you want to mount a system to a wall)
Take notes during the installation, e.g. where each sensor is, so you can troubleshoot remotely