Don't try to patch it yourself while water is flowing. Tape, epoxy, and pipe clamps won't hold at full water pressure. Shut off the main first, then the plumber can do a real repair.
Don't turn the water back on to "check if it's stopped." If it was burst, it's still burst. Leave the water off until the plumber has made the repair and tested it.
Don't use a wet vacuum on water that's touched electrical outlets or appliances. Turn off electricity to affected areas at the breaker panel first. Water and live electrical are a lethal combination.
Don't start ripping out drywall yourself. Let the plumber diagnose the leak location first — often the visible water isn't where the actual burst is. A restoration contractor should handle any demo work, with coordination from your insurance.
Don't accept the first plumber quote without an itemized breakdown of what's included. Even in an emergency, you have the right to an itemized quote. Topline always quotes upfront before any work starts.