my quick-fix routine before calling the plumber

I learned the hard way that plumbers charge a fortune even for the simplest stuff, so now I have this little routine I do before I pick up the phone. First thing, obviously, shut off the water supply (yeah, learned THAT one real fast lol). Then check under sinks and around toilets for leaks or drips—sometimes it's just a loose connection you can tighten yourself. Also, plungers aren't just for toilets; they've saved me from sink clogs more than once. Curious if anyone else has their own go-to steps or tricks they swear by?