How do you fight an enemy?
stats at start
Average survival time
usual death cause
Well, these are some of my tips and tricks:
Foreword: DF adventures are nasty and unforgiving in many levels and they currently rely a lot on fighting and braving your path across sites of interest, so I personally recommend grinding if you want to be a murderer, or avoid conflict as much as possible.
1.
You can start as a peasant and invest your preciously scarce points on endurance, willpower and dodging. Everything else will come in its due time.
2.
Search for a full set of leather armor if you start at a Hamlet or Hillock, and if you feel you've done enough of #3, set going to a bigger hub (Town, Fortress) as your first ingame goal; unless you start as an elf, then get some equipment ASAP in any non-elven site. As soon as you reach a town, search for adequate metal weapons and armor at the keep. Avoid copper as the plague, it's cumbersome as hell and you might not benefit that much from the sheer blunt force that adds to hammers and related weapons. When in generated dwarven fortresses, you might have to personally trade with a soldier, exchanging 'stolen' leather clothing for their metal weapons and armor.
3.
Crossfit a while with small, non-butcherable animals (wrestling them with both hands and skip frames. Bruises are expected). In 2 calendar days or less you'll be stronger and healthier than a Demigod, and rarely you'll need more than that. There's also the throwing grind, which will help you gaining some spatial awareness and a few other traits, but 0.40.xx combat is now meaty on its own, so you just might have few troubles just relying with melee.
4.
Reputation is now hard to earn, so try to find good companions and take care of them. That means waiting during an hour for them (press Z+w) after you cross a river, unless they're good swimmers; also try to keep them from being overwhelmed by enemies and outfit them with proper metal equipment. Boogeymen are now a royal pain in the ass, and possibly your only cause of death after all this will be thanks to them, so your companions' well being is crucial.
5.
Sneak as much as you can, the skill itself raises slowly and it apparently does nothing for your stats, but it might help you in the long run. Being a legendary ambusher inside a dungeon, keep or somewhere darker and deeper does a lot for your survival.
6.
Plan your travels accordingly, pay attention to the relative time/distance assumptions people make when you ask for a place ("it's a short walk to the east, it's a day travel to the sout, etc), and use that as a guide to get anywhere else. Use your waterskin only when you're crossing a desert or inside a huge cave, and while being anywhere else, only drink water from rivers and wells. Don't burden yourself with excess meat, you're not likely to consume it all in a lifetime, but always carry 5 or so food items.
7.
Fingers, toes and small parts are easier to break, and thus easier to inflict severe shock or unconsciousness on humanoid foes. Hitting legs also works when fighting against large numbers, inmobilizing a few while killing the most dangerous ones. If things err on the awful side, try to dodge and run as much as possible. That way, there might be another day to fight back.