Here is a simple short tutorial that is a good read. I would be very careful with electronic circuits but for lights, etc. a multimeter is invaluable. I would always check for voltage before I used the ohm meter function because voltage can blow the fuse or possible damage meter if induced into the ohm meter circuit(REMOVE ALL VOLTAGE BEFORE USING OHM METER ON A CIRCUIT). Think of the ohm meter as a miniature battery circuit sent down the path you choose to see if it will come back with close to the same value you sent it(understand bulbs, resistors or other components can change the ohm meter values). However you will mostly use the ohm meter to check continuity but also remember to check each conductor to ground to make sure it is free of any ground or foreign voltage. Also most automotive lights, etc. are grounded at the light so a circuit to ground will be seen through the bulb or device.
I am an expert on nothing but did retire after 35 years as a telephone cable repairman.
Larry in Mississippi
http://www.subaruforester.org/vbulletin/f85/multimeter-tutorial-49860/
