The game isn't only about mixups. But, if you realize that the point of mixups is to open your opponent up then you see that you can make a mixup off of anything.
I guess it's a hard concept to understand. But, let's say I 2k someone. They have a variety of options, but,with standard options, the only thing they can do safely to retaliate and beat me doing 2a after 2k I their own 2a. With this knowledge, I can counter their 2a, creating mindgames and mixps.
yeah, you have to take into consideration a bunch of stuff. Maybe start thinking along the lines of "I wantto do damage" and do what you think will most likely do damage at that point...even if it's something like 2k.