Done: Fix Water Shut Offs and Leaky Pipe
For me, that's any time major plumbing and/or electric is involved, which is why we had a plumber come out and fix our water shut off valve. We decided that it was time to stop playing with fire, or water as the case may be, and get the main shut off fixed. Now on the off chance that a pipe bursts, we won't need to scramble for buckets.
While the plumber was at our place we figured we'd have him do a few other small jobs. For good measure, we also had him fix the water shut off valves under the kitchen sink. The hot water shut off knob had broken off long before we move in. He replaced both the hot and cold knobs, because sometimes preparing for something to break, like a 50-plus-year-old knob, is better than calling out the plumber a second time.
He also fixed the leaky pipe towards the back of the house. The inspector thought the leak was coming from the shower run off, so we didn't think of it as too big of a deal because it was a super slow leak (wouldn't run the foundation) and was from run off water. Well, turns out the leak was from one of the hose pipes. So the plumber replaced that section of pipe and all our hose bibs while he was at it. Some were original to the house and needed to be seriously cranked before they'd turn off.
After all that, I followed up with the one thing I was comfortable doing myself: Wrapping the pipes near the new hose bibs in insulation, for the rare times when Austin gets a freeze.