To help speed up brush cleanup dip the brush in the correct solvent up to the top of the bristles before use. This will help draw solvent deep into the brush and make cleanup a little easier at the end of the project.
The "correct solvent" depends on the finish you plan to use. The directions on the can should provide more details. As a general rule use water for water based finishes. Oil based finishes such as oil-based paint, polyurethane, and varnish, should be dipped in mineral spirits. Lacquer thinner should be used with lacquer and alcohol with shellac.