Plot Holes and Thinking Sideways

I had a situation once, writing Orla's Code, where I realised a number of events could vary in sequence. In other words, A could cause B but also, if I introduce C earlier, then B could actually be the cause of A. There were knock on effects too, which could also happen in varying order and I tried to figure out what was the best sequence of events to make the most of each one. It all got confusing and blurry. So, I tried a Lateral Thinking technique that seemed familiar from the 90s.

I wrote down all the events on paper. Then I tore the paper into squares, with one event on each square. I placed the squares face down on the floor and mixed them up. Then I randomly placed them in a line. Then I turned the line over to see what sequence of events had been produced. As it happens the first sequence worked, making everything fall into place. It was a useful process to create a plot when my brain was too tired and I was too close to the problem to come up with one.

Now writing my second novel, I'm determined to be better organised with outline. Although today I find myself taking to my extra large notepad to do some brain-storming which will involve drawing circles and arrows as I try to work out what happens next... 

Here are some ideas from fellow writers when I asked what their fall-back techniques were:

Write several versions, then get a friend to read them.

Start at the end and work back to the beginning.

Write an arc for every chapter, then write the climax for each section.

How do you plot your novels? How do you work out those sticky issues?...