power switch diagram?

There are various things I want to put in my car that I'd like to hook up to a power switch instead of wiring these things directly to the battery. I'm looking for some sort of general diagram and/or instructions that tell how to go about doing this. I know the general steps like hooking up the object to a switch and then hook up the switch to a power source. Is there any site or place I could find this stuff or could someone whip out a quick diagram on the computer for me?