Park Your Car in a Safe Area - If you have covered car parking, then it's good; however, if you don't have covered parking, use a car cover. This will protect your car from the bird's excrement and sunlight.
Leave the Handbrake Disengaged - Leaving a car idle for a long time can jam the handbrakes if left engaged. It is best to disconnect your handbrakes and use tire stoppers instead.
Keep Your Car Tires Adequately Inflated - Leaving a car idle on flat tires will lead to crack on tire's sidewalls. Having proper air pressure will prevent cracks.
Disconnect the Battery - Leaving battery connected to an idle car for a long time will lead to the fast discharge of the battery. Disconnecting it will prevent unnecessary discharge of the car's battery.
Keep Fuel Tank at Full - In case of less fuel, the air in the tank will cause condensation, which could lead to rusting and other harmful effects.