Sometimes it's just bad luck. I'm no expert and I break stuff all the time, but there are a couple of things I do. If a pattern is drawn with something that seems unnecessarily flimsy I alter it to make it stronger. Add a bridge, widen a small bridge. If you're cutting something that's going to be very fragile there is usually a better side to cut first if that makes sense. An example would be this lower case e. If you start cutting with the inside line rather that the outside you stand a much better chance of not breaking the fragile part held by the tiny bridge. I'd probably also make the bridge a bit larger too. I'll sacrifice a little on looks to decrease my chances of breaking something. Especially as I get closer to finishing. Probably stuff you already know.