When preparing the wood, I recommend using ‘Wet and Dry’ type abrasive sheets for the final sanding - 120 grit will be suitable in most cases. Avoid using white spirit to clean off the surface dust; the best method is to use a vacuum and a soft dry brush. To help create a fine finish you could raise the grain before the final sanding. Start by dampening the wood with a thin film of water. Once dry, a final sanding will restore the flatness ready for applying the dye.