Clean the faucet with dish soap and water and dry it thoroughly before setting it on the sink deck.
Roll a small amount of plumber's putty into a ball in your hand. Manipulate the putty until it is soft and pliable, then use your palms to form a long, skinny piece. The putty should look like a thin bread stick.
Push the putty around the bottom of the faucet body and escutcheon.
Set the faucet onto the sink deck where it will be attached.
Tighten the faucet mounting nuts from below. The excess plumber's putty will be pushed out from the edges of the escutcheon. Clean around the faucet with a rag and discard the excess plumber's putty.
Wash the sink deck with dish soap and water.