Correct way of powering Arduino Uno through a 12v Car Battery

Using Arduino Microcontrollers
1

I would like to know the correct and safe way to power my Arduino Uno in my car.

2

5V adapter (cell phone charger) plugged into the power socket (what used to be the cigarette lighter). Newer cars also have 1 or more USB outlets, often between the front seats in the armrest/console.

3

Sorry, I don't want the wires sticking out so what I wanted to do was to make it go to a switch from the battery, to the Arduino board. Just trying to keep all the wires hidden and don't want to use the Cigarette lighter.

4

I use an OKI-78SR-5 on my boards to convert the 12V battery to 5V. It cost more than a liner but I like to keep the battery charged.