The fount from which all stories – well, all the BEST stories – flow is characters. Everything that happens in a story has its birth in what happened in ALL these characters’ lives prior to page one.
And the experiences, events, and people of their past all falls under one heading: it’s all BACKSTORY.
Why your sleuth can solve a crime can be traced to one or more things or people from their “life” prior to the story you are telling.
The reason why the victim was robbed, framed, killed – why the murderer committed the crime – goes back to a seed that was planted, grew and flowered in their past. We aren’t talking flowers, unless a flower show competition or plant genetics is involved, but the things that made them the character you hired for your story.
That past, that backstory holds a wealth of information to use, to warp, to weave, to twist, or simply deal with head on as the manuscript rolls forward.
Don’t forget to use it.
Don’t forget that, since the NANO competition is for a first draft, it is also possible to hone that backstory, shift it, change it, enlarge upon it.
The only thing you shouldn’t do is deliver it all in an “info dump”. Drop bits in lightly. Scatter them like raindrops in a light breeze.