I’m new to Empire, (and larping in general!), and I was just wondering what Nation the following character outfit would best suit?
A crimson cloak with a bone mask. (Perhaps one belonging to a deer?) With a brown tunic, and a dark brown leather chest plate.
Welcome along Speedy, to the hobby, the game and these Forums 
To answer your question, that sounds like a Wintermark or perhaps Varushkan outift. These are both nations that wear a fairly earthy palette (all the browns), with offsetting colours (such as your red cloak), and occassional trophies of past deeds (a deer bone mask would go well there).
However, it’s possible to tweak a lot of basic outfits towards one nation or another with accessories or trim, so my advice would be to pick a nation first and then adjust your outfit to that.
When are you planning to come to an Empire event?
Have you looked at the various nations on the wiki (just the top pages for a first impression)?
Do you have any character concepts or ideas from films/books/other settings which may nudge you towards one nation or another?
Thanks for the info. I’m planning to attend this summer, and yes. I have had a small look at some of the nations, but just wanted to double check.
I’m decently big on D&D, so I’m thinking of playing a sort of hotshot adventurer character, sort of a Han solo like in personality. The type to purposefully add wear and tear to his clothing to make himself look more experienced.
Hello and welcome
I’m going to go slightly contra to Geoffrey here with suggestion
Don’t try to go “costume, then Nation,” do it “Nation, then costume”.
Each Nation has very distinctive kit briefs that allow for almost snap visual identification, alongside certain RP cues that get flagged in the briefs.
Have a proper nosey at the Nation briefs and the wealth of photos on the Nation look and feel pages, as both should provide you with some more ideas and far reaching kit goals
Be aware that kit is something that’s encouraged to be a continuous development dance
You’ll discover, as you play, that certain things work for you, as you’re spending 12+ hour days in a field in the great British weather, and what you think suited your character might not.
This is good, normal, and very supported.
A hotshot adventurer type fits in a lot of Nations, as Empire really (attempts) to avoid the very D&D class based determinism of say “I am rouge. I do sneak. Sneak is what I’m good at”.
Instead, you get archetype, which are more little things to nudge character goals and what you might want to nosey at.
Using the Nations mentioned above, a cocksure adventurer type in Varushaka might be a wagon raider, always out from the Vales protecting wagon trains through the woods…or lovingly ensuring goods are “liberated” from Druj supply lines.
But in Wintermark, they might be an icewalker, venturing out onto the icy wastes of Sermersuaq.
Just to add that for Varushka at least, we’re not earthy tones - we’re rich jewel colours, with embroidered trim. My first instinct would be Wintermark, but I do think that Squeek is right - trying to force a costume to fit into a nation is tricky, as the kit briefs are distinct for a reason. Kit is also aspirational though, so you can come along with something basic but appropriate and then build on it.
What you don’t necessarily want to do is choose a nation to fit your kit, and then find that you don’t really like the vibe of it! It’s better to choose a nation that you like the sound of, and then come along with some appropriate base layers.
As also stated, a hotshot adventurer could fit into any nation with some tweaking to fit the different cultures. But a lot like Han discovers, you’ll find that you won’t get very far if you want to lone wolf everything! 
Thanks for all of the information. I’ll look more into all of the nations, and make sure I’m choosing one I really like the sound of, and then I’ll re-design my outfit concept when I find one that really stands out. Looking forward to coming this summer!