Required:
Glow ignitor. I use a hot shot type rechargeable.
Fuel and pump. I use a manual pump that velcro's to the side of the gallon fuel jug.
Chicken stick.
Extra wing attachments (either rubber bands or nylon bolts)
Windex and paper towels for cleanup.

Nice to have:
Electric starter. I use the starter with the battery attached to the bottom of it.
Extra glow plugs and glow plug wrench.
Extra prop and prop wrench. I use a 4 way prop/glow driver wrench.
Whatever screw/nut driver to remove/replace the spinner.
Volt meter to test how much power is left in the receiver battery. I use an expanded scale voltmeter.
Field charger. I have one. The only time I use it is if I am at the field all day long.

Things to leave at home:
CA and any other repair stuff. If it is damaged enough to need glue for repair, pack it up. Check it more thoroughly for damage at home. The only "repair" item I might have in my box is clear packing tape to cover a hole or lifting seam until I get home.

Of course this assumes that you are flying glow, not electric.