It is possible to achieve a high-quality finish using high-quality products and accessories such as premium brushes and rollers. However, it is difficult to avoid brush or roller marks during application. On the other hand, a well-executed spray application will produce a perfect result. 

Despite this, many DIYers are able to achieve exceptional brush or roller finishes by following some practical tips. 

It is important to properly prepare the wood surface by sanding with the right grit and removing all dust. Finishing products must be carefully prepared by diluting if necessary and following the recommended viscosity. It is also important to follow recommended drying times and apply an appropriate product thickness. 

A sanding with 400 grit should be done between each coat of varnish, sealer or lacquer, and the surface should be cleaned after each sanding. 

By following these steps, a superior quality finish can be achieved. Finally, it is crucial not to neglect the quality of the accessories and products used, as there is always a valid reason for the price difference between two varnishes.