1. If you mine out really big rooms, be sure to build supports (or leave some stone tiles behind) or you will get cave-ins.
2. Build lots of bridges over the cave river to make sure the seasonal floods don't sweep your dwarves away
3. Be careful with the chasm - either redline it with magma, or keep it well trapped.
4. Start farming as soon as you possibly can - you're likely to get a big migrant wave near the end of Autumn, and you cannot do any farming during Winter.
5. Keep your bag stockpiles far away from your plant processing workshops and dining rooms - dwarves will always choose the nearest bag for storing seeds, even if there are a dozen other bags that contain a single seed each.
6. If you decorate barrels or bags, you won't be able to use them for making dwarven syrup, extracting quarry bush leaves, or milling (and possibly even brewing). They'll still be usable for food storage and gathering sand, though.
7. Keep a set of craftsdwarf's workshops somewhere and surround them with stone stockpiles that only accept a single type of stone. With the number of nobles you'll get (and the mandates they'll make), you'll be needing to make lots of items out of specific types of stone.
8. Grab a copy of Dwarf Manipulator
here - it's not quite as versatile as Dwarf Therapist (and the text interface is a bit clunky) and it isn't quite as robust (always make sure the game is paused, or you might get crashes), but it's invaluable for managing labor assignments. As an added bonus, you can even use it to make your soldiers use bows, daggers, and whips/scourges.
9. If you're bothered by the inability to forbid items or the inability to melt/chasm stuff without going into the Stocks screen, get a copy of
2d forbidder. As with Manipulator,
10. I recommend
autoforbid as well, just to make sieges slightly easier to deal with.
11. Make frequent backups of your saved games, since they can easily get corrupted during crashes. This is especially important if you're using any of the above 3 utilities, since they themselves can cause crashes.