FLOWCHARTS COME FROM THE EARLIEST DAYS OF COMPUTING, BUT THEY ARE A GREAT TOOL FOR PLOTTING OUT HOW TO MAKE YOUR INTERACTIVE STORY WORK.
I made this one at itch.io which
looks nice and neat, but you could
make one with whatever method
you liked best, hand-drawn, in word or any other method that works for you.
even though this story is very short and simple, you can see it still needs quite a lot of mapping out to be easy to follow. imagine how complex a story with multiple threads and characters can become! this illustrates why preparation is very important if you want to avoid getting bogged down. for this project, keep your story very simple too.
if you need something to get you started, I have made an empty sample chart you can print out and fill in.