Flow charting is the way to do it as far as I am concerned.

I have a young guy working for me that asked me to look over his code as it was not working correctly. I looked at what he had and asked him to tell me exactly what he was trying to accomplish where or what was supposed to be happening. He was getting himself confused while trying to communicate the procedure. ( I will have to give him some credit as this is a project that involves several python scripts running on a server collecting data from a PIC and displaying in a web browser, so having trouble is expected).

I asked him for his flow chart or outline and he did not have one to show me, he was trying to keep it all in his head. I sent him away telling him t make a flow chart or outline, then we can talk about the code.

Flow charting is also a good method when there are multiple people on the project, task can then be divided out.

So keep doing the flow chart, it is a tried and true method.