How not to break your flow while drafting
When you’re writing, you’re bound to notice things about your writing that need fixing, places where you want to do more research. Background characters whom you haven’t figured out names for, etc. Now you could go ahead and stop what you’re writing and go fix it, research it, whatever.
Or, you can just mark it in-text. And then keep writing.
What I do usually is <<<insert comment here>>>. Having three of the little arrow things makes it really easy to find with the find and replace function, and it also means that I can make my comments as long as they need to be, and keep them distinct from the actual prose.
Not all authors use this marking method (actually I’m pretty sure that a lot use TK to mark the spot), so I encourage you to figure out what you think is most useful and try it!