Clean it before you use it!
Cleaning a new badger hair or boar hair brush is simple and only takes a few minutes but it is important to start out clean for obvious reasons. A new brush out of the box will quickly remind you that it is made out natural animal hair. The cheaper brushes will carry an odour for several shaves before it finally goes away. It also helps to remove loose hairs and dust from the manufacturing process. If you purchased a synthetic brush, you simple need to do a quick wash to get any fiber dust out of the bristles. To do this I just use an antibacterial soap and hand lather for a few minutes and you are good to go.
Paul H. films has a great instructional video on how to clean a new brush that is really good to watch. So take a few minutes and learn how to clean your new brush!