Wrap the male threaded fittings with Teflon tape or pipe dope to improve the seal.
Your new faucet may come with a mounting gasket or the instructions may direct you to create a base using plumbers putty. If directed to use putty, roll out a length of putty between your hands, about 1/8" in diameter and long enough for the entire perimeter of the base of the new faucet. Apply the putty gently to the base and then place the faucet into position on the sink. Gently rock the faucet to create a bond between the faucet and the sink. Make sure the faucet is level and there are no gaps in the putty. Gently scrape away any excess putty.
From beneath the sink, slide the washers (if any) onto the faucet and fasten the lock nuts securely. Do not over tighten the lock nuts.
Now connect the water supply lines. You may be able to use the old supply lines or you may need to install new ones. We like the flexible, braided stainless steel supply lines because they are very easy to work with. Professional plumbers often use rigid tubing because it is cheaper. However, at a plumbers hourly rate, if he spends just five minutes cutting and bending tubing, it already is costing more than flexible tubing.
Screw the supply line connection to the faucet, making sure that you connect cold-to-cold and hot-to-hot. Insert the drain lift rod and connect it to drain pop-up assembly. Test the lift rod to make sure it seals and opens properly.
Remove the aerator so that any debris in the water lines can be flushed out. Turn on the water supply valves and then turn on the faucet for a few seconds. Replace the aerator and then inspect the connections for leaks.