How do I properly apply polyurethane to a wooden surface for a durable and protective finish?

To properly apply polyurethane to a wooden surface for a durable and protective finish, follow these steps:

1. Sand the wood surface to remove any imperfections and create a smooth surface.
2. Clean the surface to remove any dust or debris.
3. Apply a coat of polyurethane using a high-quality brush or applicator, following the wood grain.
4. Allow the first coat to dry completely before lightly sanding with fine-grit sandpaper.
5. Apply additional coats of polyurethane, sanding between each coat for a smooth finish.
6. Allow the final coat to dry completely before using the wooden surface.