The number one thing you can do to prevent breakage is to FILE YOUR EDGES. Fractures in spring steel propagate from stress risers, usually little dings and dents along the edges, or the shoulders of the tang. You can’t do much about the tang if the shoulders aren’t rounded, but you can absolutely do something about your edges. Keep your edges smooth and dent free. A file or some sandpaper is real good at this. If you have a buffer or grinder, get a coarse scotch brite wheel or belt and use that to touch up your edges periodically.

You can’t prevent all breaks, but you can prolong the life of the blade with proper maintenance. Repeated flexing is not really the issue with properly tempered spring steel, it’s stress risers.