I tend not to do this straight off, but gradually shift overtime to an aboveground fort.
As has been said previously, you need lots of stone. lots. I suggest walling off your fortress with a largish aboveground area. Of course include cage traps in holes in the wall every now and then so that your army has good quality training after they have disposed of the rest of the invaders that decide to try and ruin your fortress. (or town, eventually) Obviously, include two 3-z level ramps on either side of the wall, with a road (which will become your town's main road) leading to one, and a large bridge connecting the ramps. (bonus if there is water or arena below)
Next I build the nobles' houses, just so they can see the extent of damage for themselves if invaders come. Make sure you build a stone block stockpile next to the construction, otherwise the silly dwarves take years to build things. (make the non masons move all the blocks and stone) Be sure to include a few windows in the house, as no house has only walls!
Then make massive apartment buildings, with dining rooms every now again. You can designate different areas of the town for different industries. If you like order, or you can make everyone seem chaotic my building stockpiles (in storerooms, of course) at opposite areas of the town which need the supplies.
Make sure hallways go right to the end of a building, (facing a street) so that when another building on the other side is constructed, so can connect the two with a bridge. Have some more fun by building a jail on a high floor of a building only accessible by bridge.
I enjoy connecting each bridge to a single lever, and see how productive things are when there all the bridges are down.