Here you'll find our guide for Koiken Otome.
There's no enforced playing order, you're free to do as you like. However, Yves and especially Akane are the most "relevant" to the overall story and world. It is suggested to play Touko's or Akane's route first, as some of Touko's gets nonchalantly spoiled in the others. There are no bad ends. Choice numbers are included in the brackets.
The general game structure is: Prologue -> Common -> Individual Routes
-  Do you have a plan or something?
-  I agree.
-  Wholeheartedly support her.
The choices to get into a specific characters are all contained in Common, which starts right after the OP video. They're all somewhat obvious, and there are no bad ends, so there's no harm in picking whatever you feel like. However, sometimes the option for Yuzu's route isn't available if you don't make the indicated choices in the prologue.