Nobles are always treated well, provided multiple layers of security, and must absolutely be protected, safe, and have lavish throne rooms.
Dwarves are to be treated well, kept safe, healthy, well fed, and drunken at all times. Its okay if a dwarf occasionally drinks some water instead of booze until another still comes online, but the idea should be to have stills running continually.
All dwarves get large, 3x3 rooms. Enough rooms for the entire fortress is ideal, however as I run very large fortresses (250+ dwarves) the population often times outstrips living space, in which case there are slums scattered around the underbelly of the fortress until an apartment vacancy opens up.
All dwarves are put into a caste depending on their skills upon arrival to the fortress. At the top are the nobles, then forge lords, then stone lords, jewelers, scribes (mechanics + medics), merchants, and then the lower class woodsmen and finally the commoners. Upper class dwarves are not expendable. They are above hauling. Commoners make up 80%+ of the fortress and do all of the gruntwork as well as form the military.
All dwarves trying to move from one caste to another via strange mood will be dealt with, severely. Exception: possessed moods provide no experience, and so those dwarves are allowed to complete their artifacts. A fey mood peasant trying to join the merchant class by claiming a workshop will be put down.
No bone artifacts. Because they're bugged. All dwarves attempting to create a bone artifact are to be put down.
No excessive use of traps. Traps must be used in moderation. No drawbridge crushing traps, those are lame.
No killing of caravans. Caravans must be protected if at all possible.
No killing of migrants. All migrants are welcome. I can always use more commoners to haul things around or to join the military.
Steel weapons and arms only. No better, no worse. Masterworks only. Only steel. All military equipment failing to be masterworks are sent back and melted down.
All weapons and arms must be decorated with obscene levels of bling.
A plumbing, water purification, drainage, and ventilation system must be built. Safeguards must be built to ensure that should building destroyers run amok and destroy every single building object, water/magma will passively drain away to prevent fortress flooding, or to limit flooding only to small areas.
All important rooms must be more than one Z level tall. Preferably 4-5 Z levels tall.