I second the lug nuts and brakes! I've had two problems with mechanics working on my vehicles. My first car I had a mechanic put brakes on it and he didn't look at my brake lines. Needless to say I was pulling into a parking lot and the brakes went out, nothing bad happened because I used emergency brake and slammed it into park.

Just recently (fall 2011) I had a mechanic put shocks on my truck (91 dodge w150 w/ 3" lift) and the damn driver's side rear tire flew off (RIM AND ALL!) doing 65mph on the interstate pulling a trailer with a lawnmower on it. Not fun. Had to run 1/8 to get the tire, luckily no one was beside me.

I know, why didn't I do the shocks myself since it's easy? Was busy with work.