Usually my embarks are always tweaked at least a little bit to account for what I *think* I may face.
For "normal" embarks - given some initial indications of metals, supply of wood/burn able fuel, and the presence of a brook or stagnant pools:
2x 'Delver' - Proficient Miner, Competent Mechanic; quick expansion then gadgets and gizmos
1x 'Supplier' - Grower, Brewer, Herbalist
1x 'Stonefist' - Mason, Engraver, and Architect (only two points... I heard it speed up building bridges)
1x 'Forester' - Woodcutter, Carpentry... a few points in the Axe skill and functions as second 'Thane'
1x 'Outfitter' - Armorsmith, Weaponsmith
1x 'Thane' - Proficient Weapon user, Competent Armor & Shield User, the rest in Teacher.
This build allows for relatively rapid expansion with the two delvers, the supplier allows me to be self-sufficient until I hit around 30-40 dwarves and then need more growers. The outfitter allows me to have quality equipment ready when I find materials and the Thane with teaching skills gives me a good base for having a well run and well skilled militia. The Thane usually is skilled in a sword or spear to balance out the choppiness of the Axe wielding woodsdwarf/thane. The rest are just there because high quality beds, engravings, and cabinets help offset any initial grumbling should various accidents, surprises, or otherwise occur. Overall it's a fairly standard, balanced build. It can handle most of the needs for a fortress well until I receive a substantial amounts of new migrants.
As an aside all the starting seven are given those job titles after a 'Caravan' identifier telling me they are indeed the founders if I need to search more quickly for them or find out if they are still alive.
For "dangerous" embarks having either good chances of early visitors or suffering from plagues of unearth the builds as follows:
3x 'Thanes' - Proficient Hammer Weapon Skill, Competent Armor and Shield Users
1x 'Outfitter' - as above
2x 'Delvers - Miner, Mason, Mechanic
1x 'Quartermaster' - Grower, Brewer, Trader, Appraiser, Judge of Intent (1 points enough)
The blunt weapons of the Thanes help me ensure I'm not increasing my troubles as far as making more undead pieces to deal with, The Delver and their picks can act as an additional 'reserve' should the 3 thanes not be enough. The Outfitter keeps them as kitted up as I can manage given the materials on site. The Quartermaster is a catch all 'provider' to allow for me to help keep the dorfs fed and liquored up while allowing to take full advantage of any traders. After all if I'm going to try and colonize a cursed piece of zombified hell on earth I'm damn well going to take full advantage of anyone stupid enough to follow me there.