If you are replacing a bath faucet here's a plan by the numbers. It should also have instructions with it.
1. turn the water supply off under the sink (hot and cold) the little valve on the hot water side may not shut off completely, in which case go to the main valve where the water line enters the house, or at the water heater.
2. Take the old faucet off by removing the supply lines and then the lock-down nuts with a faucet wrench , a specialty tool for working in the tight space below the sink. If the lock-down nuts will not turn, you can drill them on one side and split them with a screwdriver.
3. Lift the old faucet out.
4. Use the enclosed plastic gasket or put a bead of plumber's putty around the perimiter of the faucet base.
5. Set the faucet in place and have a helper to hold it straight and centered. If help is not available just tighten the new lock-down nuts finger tight, realign the faucet, then tighten with the faucet wrench.
6. Attach the supply lines to the new faucet, turn the water on and look for leaks.
7. Unscrew the flow limiter and screen from the underside of the spout.
8. Run the hot and cold water for a full minute to remove any debris that may have fallen in the holes or become loosened in the pipes.
9. Replace the screen and flow limiter set. If you must tighten it with pliers, put several layers of cloth on it first to eleminate cuts and scrapes. Do not over grip the pliers; it will crush.
10. Congratulations! You're finished. Enjoy.
By the way, if you live along I-40 between Nashville and Sevierville and have any trouble with the faucet, let me know; we love to have an excuse to go to the Smokies.