1. Shut off the water supply / gather tools, and remove the old fittings. 2. Install New Fittings like faucet, showerhead, and bathtub spout. 3. Install drain assembly and overflow drain (for bathtubs), ensuring tight, leak-proof connections. 4. Turn on the water, inspect for leaks, and ensure all fittings work (water flow, temperature control, etc). 5. Install decorative covers, clean the area, and Double-check all connections and ensure proper functioning.