<human>:  I am building a wooden birdhouse and I need to know how to sand it properly - what materials do I need and what are the best techniques?
<bot>: You will need sandpaper, a sander or sanding block and a dust mask or respirator. Depending on the type of wood you are working with and the desired finish, different grits of sandpaper can be used. For rough sanding, use a coarse sandpaper (grits of 40-60) and for finer sanding use a medium-fine or a fine sandpaper (grits of 100-220). The best technique for sanding is to start with a coarse sandpaper and move to a progressively finer one, until the desired smooth finish is achieved. Be sure to sand parallel to the wood grain and sand lightly, using circling motions to avoid leaving visible marks. Finally, vacuum the surface of the wood to remove any wood dust that could interfere with the finishing process.