In the previous tip in this series I suggested that you plan at least the major action of your plot. There's a simple tool that makes this much easier: a pack of index cards (or a bunch of sticky notes).
Write each major development in your plot on a card. You can use colored cards to keep track of the various strands of the story (for instance, white for your main plot, light blue for one of your subplots, light green for another subplot). Another option is to assign a color to each of your major characters so you can track them easily through the plot.
You can pin these cards to a cork board or spread them out on the floor (the latter is not advised if you have pets or young kids). Alternatively you can use sticky notes, like Post-It notes) and put them on a wall or door or whiteboard.
The advantage of this method is the ease with which you can move things around. Should your protagonist tell his best friend about the robbery he's planning early on or just before he does it? You can put the card with that development in the first position and see how it affects the flow of the story, then move it to later and assess it again. You can also easily add or remove scenes.
Naturally this works just as well for organizing the content of a non-fiction book.
Some computer programs allow you to do the same thing but you're limited to the size of your screen. Maybe I'm old-fashioned but I like being able to spread out the cards and see them all at once. Either way, for maximum flexibility in building your story this method is hard to beat.
(For more guidance on how to plot and write your novel, see "Your Creative Writing Masterclass," published by Nicholas Brealey and available from Amazon or your other favorite bookseller.)