Writing outside my comfort zone

I've been approached to write something new between edit sessions and have decided to take up the challenge. I'm excited to try writing something, but it's not attached to The Paladin, like my last two short stories were. It's certainly in my area, between my older stories that were high fantasy and my current urban fantasy novel, so I'm not terribly worried, but I've decided to pursue this story as a specific genre I've never touched: mystery.

I love me a good Sherlock Holmes short story (more Arsene Lupin when I have the options) but I've never actually written anything like this. I'm excited, but also anxious. I've been poring over resources online to learn the ins and outs of writing a mystery (pro tip: write backwards) and I've got, maybe 40% of the plot outlined in my head. 

It's a lot harder than what I've been doing, which is good. The major problem is this will take some time. It's a mystery with fantasy elements, which brings things into a more familiar area for me, but it also means I have a whole slew of extra things to consider.

So far, the best advice I've found, which I'm following, is that I'll need two outlines: one for what the reader will know and one for what is actually happening. To quote the Dude, there will be a lot of ins and outs. I already have a bunch of visual aids to help me keep track of things and I haven't written a single word.

So what about you guys? Ever try to write outside your comfort zone? How did you approach it?

​DFTBA