Probably the easiest way to do this, without burning up a 10 amp meter is to locate your panel/fuse box. Place you meter in 10 amp mode. Remove 1 of your 12 volt fuses from its place in the fuse box. Set the fuse aside. Touch one lead to one side of the fuse holder, and the other lead to the other side of the fuse holder.
Now your meter is in series with the current flow and will show you the amps for that circuit. You can check individual circuits this way. If you want to check individual lights or equipment on that circuit remove the light, or shut of the equipment and note the difference.
If the circuit you removed the fuse from has a fuse rating of more than 10 amps you take the risk of blowing the fuse in your meter. Of my fuse box, only 1 of 15 has a fuse of more than 10 amps.
This way you can check individual circuits and get an idea of what each circuit is using. Total them up if you want to know total amp draw.
