How can I achieve a professional finish on my woodworking project by applying polyurethane?

To achieve a professional finish on your woodworking project using polyurethane, start by sanding the wood surface smooth and clean. Apply a thin coat of polyurethane using a high-quality brush or cloth, following the wood grain. Allow it to dry completely, then lightly sand with fine-grit sandpaper before applying additional coats for a smooth and durable finish.