Proper brush care is important, as those brushes are not cheap and keeping them in good condition is the best way to make them last.
Even at that, you'll want to replace your brushes - at least once a year or every 5-10 paintings depending on how rough your surface is or how well you care for those brushes. Your brushes matter - you can't get a nice crisp line from an old, frayed brush! Keep those old, frayed brushes for some of the messier, softer edges you might want to create in the background of your piece.
Hopefully this video helps you to care for your brushes. NOTE: I usually wear Medical Grade Nitrile Gloves while doing this to protect myself.
Here are links to the cleaners I recommend in this video:
1) For OIL BRUSHES (you can use this for all brushes, but I prefer it for my oils): Jack's Linseed Studio Soap
2) For ACRYLICS and WATERCOLOR BRUSHES: The Masters Brush Cleaner is a cake of soap in a little container. Easy! Rub the brush on the cake to get the soap on the bristles, then work it into your palm. I demonstrated using Pink Soap by Mona Lisa.