Even if your brushes are not the fancy high-priced Kolinsky Sables, taking care of them should still be a high priority. 

Why? 

Because taking care of your brushes will help them last longer which means you won't have to replace them as often. And that my friend, saves money. Who doesn't want to save a little money these days? 

Here are 5 things to NEVER do to a good paintbrush: 

1. Don't leave your paintbrush in standing water- Leaving your brush in a jar of water can cause the handle to swell and crack if it's made from wood. Prolonged soaking in water can also cause the glue holding the tuft hairs to loosen causing the tuft hairs to fall out of the ferrule. 
2. Don't use watercolor brushes for other mediums -Oil paint, acrylic paint, as well as ink may contain chemicals that will damage the brush especially if it's made from natural hair. Acrylic paint and oil paint can also leave a residue in the brush that may stiffen the tuft hairs and render them useless for watercolor painting. 
3. Don't cut the tufts of watercolor brushes- Watercolor brushes have small splits at the tip of each hair called flags. These splits help the brush hold more water and paint which creates better painting performance. Cutting these flags off will reduce the performance of the brush. Brushes are also skillfully shaped for a specific purpose. Cutting the brush tuft will alter the shape and it alters its ability to be used for its specific purpose. 
4. Don't apply masking fluid with a good watercolor brush- Using a good watercolor brush to apply masking fluid is a big no-no. Masking fluid is made of liquid latex and will gum up the tuft hairs and seep into the ferrule of the brush. This will cause the brush to lose its flexibility and be useless for painting. Always use an old brush or an applicator made specifically for applying masking fluid.
5. Don't forcefully stab at the watercolor paper with your good watercolor brush- Stabbing the paper with your brush can cause damage to the tuft hairs, bending and breaking them. This will cause your brush to become misshapen and cause its brush strokes to become ragged instead of smooth. 

Always take good care of your brushes and they will last much longer. If you have any questions about taking care of brushes, please let me know and I'll be happy to help.