What are the best techniques for applying vinyl wallpaper glue to ensure a smooth and long-lasting installation?

To ensure a smooth and long-lasting installation of vinyl wallpaper, the best techniques for applying glue include spreading an even layer of adhesive on the wall using a paint roller or brush, allowing the glue to set for the recommended time before applying the wallpaper, and smoothing out any air bubbles or wrinkles with a wallpaper smoother or squeegee. Additionally, following the manufacturer's instructions for mixing and applying the glue can help achieve a professional finish.