How can I ensure that the wood filler I use hardens properly for my project?

To ensure proper hardening of wood filler for your project, follow these steps:

1. Choose a high-quality wood filler product that is suitable for your project.
2. Mix the filler according to the manufacturer's instructions.
3. Apply the filler in thin layers, allowing each layer to dry completely before adding more.
4. Sand the filled area to smooth out any imperfections.
5. Allow the filler to cure for the recommended time before painting or staining.