Check the condition of the supply lines for leaks or obvious wear. You may want to replace these at the same time you replace the faucet. Most new faucets come fully assembled, some even with inlet hoses attached. Check with the clerk at the hardware store to be sure.
A basin wrench will make this job much easier.
Once this is done, wipe away any excess residue silicone. Ensure the inside of basin cabinet is dry.
It may be handy to follow the specific instructions from the manufacturer for your new faucet, as where and how many of these nuts need to be placed will vary between faucet styles.
