While I agree that optimization is good to think about, I also think it's important to optimize the amount of fun I'm having, not the ability to produce some specific good quickly. A lot of my "optimization" choices come from that thinking. If I have a general game philosophy, it's that incremental mood boosts can save you from a tantrum spiral.
Except where noted, I nickname my starting dwarves after their favorite drink or a preference I can acquire more easily through trade. Incidentally, I'll also name any professional dwarves with the same system, and military dwarves get nicknamed their actual name (So Ezum becomes 'Ezum' and this easily sorts important dwarves from peons in Therapist).
I pick which dwarf gets which job based on their item preferences.
My TreeKiller, for example, is the one who likes axes or something made of wood, etc. He'll get Carpenter 5, because everybody interacts with the stuff he makes, so it might as well look nice and give people a free mood boost. I'll also be selling off anything he makes that isn't masterwork, until we have masterwork splints, crutchs, step ladders, wheelbarrows, beds, bins, etc. He also gets 1 in the entire Wood Burning -> Soap tree. (Elves are clearly dirty hippies because they can't make soap!). With stone pots, I no longer make wooden barrels except during the first year.
The Miner/Mayor is whoever has the least offensive possible mandates. He gets Miner 1, Appraiser 1, and social skills appropriate to his personality.
Mason 5 / Animal Handler 2 / Caretaker 3, usually. In my current fort, he loves rope reed paper, so he has papermaker 1 instead of one of the other points. I want my mason making doors, furniture, and statues asap, particularly because my preferred method of learning about the world is with the new(-ish) Details tab on the statue. I start by making statues about our civilization, look at them, and if I see someone do something interesting, I make more statues of him. I keep a record of this search visually stored in a statue garden. They get quite maze like and delightfully organic.
My Stonecrafter gets Architect 5, again on the argument of nice buildings inoculate against tantrums. He'll be nicknamed something that reminds me of what he likes to craft the most.
Next I look for my Mechanic/Glassmaker/Potter/Bonecarver. He's my odd jobs guy.
The Doctor gets Diagnostic 5, brewer 1, and 1 point in all the other medical skills.
The Herbalist 5 gets 1 grower, 1 cook, 3 leatherworker. High Herbalist means more seeds from each square I gather from, which makes my above ground crop farms stop spamming cancellation messages sooner. I try to make sure my still is producing all the alcohol preferences of my starting 7 and any Legendary Dorfs that migrate in. It makes them happy, but it also gives each fortress something memorable that connects them.
3 Picks, with the mason and stonecrafter working them until the soil layer, bedrooms and first workshops are completed. The soil layer has all the farming and treekilling stuff.
2 axes, because f*** those keas, dammit, I won't be fooled again.
Pets for each dwarf who can reasonably get one, especially egg laying ones.
3 Females and 2 males of any animals I'm breeding for yarn, leather, eggs or meat. That's part redundancy, as has been mentioned, and part to make sure I always have something to quickly kill if I need leather or bones for a Mood.
Notably, the dogs get trained up to wardog, and then the uglier of the two males gets gelded. I used to chain the gelded dog by my entrance to sniff for ambushers, but I felt bad about it, so now one dog gets his freedom and the other dog gets to keep his balls.
Also, since time immemorial, one male cat gets sacrificed to Armok if we manage to survive to the first spring. I'm quite pleased that I can now proudly display the cat skull totem we make of him on a pedestal in the dining room. The sexiest female cat gets pastured in the Soil Layer before the doors gets put in, so she has the run of the entire floor.
I start with one bar of everything that might be needed for a mood, 10 each of the hospital stuff, and I abuse the meat barrel & sand bag exploit.