Ya I just wish it went that easy. What I struggle with is getting to the point of using said mix up with out being poked out.
It sounds like you're not getting her pressure down, because her mixup is a straight 50/50 and they can't guess right every time. It's actually tougher than it looks to pressure and condition your opponents with cassie. I recommend watching sonicfoxe's cassie, but the next best thing is it think about what you're not using.
I fall into a repeatable pattern sometimes, and that can cost you games. Say you always b12 check after d4 hits, and they respect it. You're always ending up -7 in their face and losing the initiative. Well you can start doing things differently after the d4, like running up throw, run up f3, or run up 212. Maybe risk armouring or ex nutpunching after you're minus as a risk, if you feel they'll push buttons. Use different strings too, b2121+4, 331, 332, strings that your opponent hasn't seen can confuse them and give you a small advantage (provided it isn't a terrible string).
Keep playing more games and you'll naturally start adding things to your offense. Watching better players speed tracks that, but with Cassie there aren't many options. I can't think of one major travelling player that uses her besides fox.
