While reading juddster's post this morning I was reminded of many other electrical system related mishaps I've read on the forum over the years, from crossed light wires to wrong pins on RF harness connectors. My question for experienced folks is this: How much testing do you do of your electrical system before hooking it up to the battery? What about before engine first start? Any advice you'd give to a newbie who've never worked on vehicle electronics? Any parts of the car to pay special attention to? Any areas that would be a pain in the *** to debug after the engine is in? What about problem prevention down the line such as wires rubbing on the frame and wearing out protective coatings?