My current fort is doing fairly well. It's in its fourth year, and has seen only two deaths so far: an engraver who was unlucky enough to get heartshot in an ambush, and a carpenter who was found dead, completely drained of blood.
The drainer was my first vampire. The carpenter had been sleeping on a hospital bed, as I hadn't carved personal bedrooms for commoners yet. The sole eye witness was a ranger who had been fishing in the hospital well. He accused a non-suspicious-looking wax worker, who had migrated into the fort quite recently. The ranger held no grudge with the wax worker, so I thought I might as well believe the witness and convict the accused. The wax worker took 50 hammer strikes like a boss, thus revealing himself as the murderer. I gave him a bedroom and locked him up. Gotta figure out what to do with him later.
Only two deaths, but a few close calls. Two of my woodcutters were ambushed near the edge of the map, by a goblin axeman squad led by an archer. I reckoned the dwarves would be lost, and made no attempts to rescue them, just assigned civilians to the alert burrow inside. The archer miraculously missed his first shot at nigh point-blank range, and the woodcutters ran for their lives. I hadn't taken into account that the forest they were cutting down was very thick, and the dwarves soon lost eye contact to the ambushers. They stopped panicking, and calmly made their way to safety through the gates, where the ambushers were shot down.
The only non-lethal injury this far was caused by a tantrumming captain of the guard. He threw a barrel towards a craftsdwarf, smashing a leg. I was a little bit worried, as my medical team hadn't had any training, and their skills were quite rusty. However, the leg was diagnosed, cleaned, sutured, set and wrapped up in cloth and cast in less than a week. Now the craftsdwarf is happily limping around with a crutch in hand, his leg healing fast. No infection so far, even though the water used for cleaning was stagnant.
I've got a skilled and armoured military up and running, and the fort supports itself. Everybody's got a large number of friends though, so I'm expecting a spiral at the first sign of trouble. The site's low on ore, and the only income of good metal is goblinite and caravans.The last dwarven caravan was sadly ambushed and scared away, so no metal industry for a while. I haven't been besieged yet, and I'm trying my luck cutting wood and hauling goblinite from outside. Might start a megaproject of sorts sometime soon.