These are my custom professions:
Socialites: Peasants with no hauling duties, for obvious reasons
Labourers: Peasants with hauling duties
Undertakers: Peasants with cleaning/burial duties
Doctors: Animal Training, Animal Care, Healthcare
Guard: Self-explanatory; while not activated, as Socialites
Soldier: As guard
Cooks: Cheesemaking, Butchery, Cooking
Brewers: Brewing, Farming
Millers: Threshing, Milling, Farming
Harvesters: Plant Gathering, Farming
Carvers: Bone Carving, Woodcrafting, Stonecrafting
Watchers: Hunting, Bowyer, Trapping, Fish-related skills
Engravers: Mining, Engraving, Masonry
Architects: Mining, Masonry, Architecture
Technologists: Mining, Mechanics skills, Siege Operation skills
Smiths: Smithing skills, excluding Furnace Operator
Woodburners (for lack of a better name): Wood Burning, Furnace Operator
Alchemists: Glassmaking, Lye Making, Potash Making, Soapmaking
Carpenters: Carpentry, Woodcutting
Home-grown dwarves must max out all social skills as Socialites before they're permitted to have another profession - immigrants immediately go into the grouping that they best fit into.
I find that having Animal Training on my Healthcare specialists massively increases their survivability during sieges, as I do not use the 'Dwarves Stay Indoors' setting for any reason, ever.
I also like having multiple groups with the same skill (Mining, Farming) as even when they have "nothing to do", they still have something to do.
Also, here's a protip for those who have not heard about it yet - if you never want to see tantrums, here's what you do: for the first handful of years, have a single 1x1 meeting area. This causes a huge dwarven doggypile if there are too many of them, as all dwarves who are not doing something will cluster into a 3x3 area and happily have a huge group conversation while prone (ie, lying on top of one another or simply in standing-room only).
This maxes out social skills very, very quickly, and causes a large number of pregnancies. (Dwarves with every social skill maxed are maxed in every attribute. Good for when the Hammerer or the Goblins come a-knockin'.)
Anecdotal observation: With every dwarf being a legendary consoler or a legendary pacifier, less than approximately 5% of your population should ever be less than ecstatic - mine are either perfectly happy all the time, searching for a magma pit or a well to jump into, or dashing their many babies' skulls against pillars in a rage.
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