In my games I usually dig a trapped entrace pathway, bring or cut a lot of wood, get my mechanic working on mechanisms, and craft a lot of spiked wooden balls for weapon traps (they basically perma-stun the goblins until they bleed out rather than outright killiing them and jamming the trap, and they are fast and cheap to build early). Then use some dogs or cats to detect the sneakers. It also usually zigzags back and forth a few times.
Usually this hallway is dug a few Z Levels down, so that I can have a marksman's box one Z level up, with fortifications looking down on the approach, with bridges in front.
As ambushes, sieges, and traders bring me various weapons, I will usually fill several wapon traps with other weapons as well, mixed in with the spiked wooden balls (the end of a 1 tile thick wall used for the zigzag will always get a spiked ball since most attackers will cut the corner tight, and I don't want it getting jammed on the first attacker). Once I get my metal industry up, it generally consists of manufacturing Steel Giant Axe Blades, segragating the masterwork ones, and melting the non masterwork down. I then fill weapon traps with 10 masterwork axe blades each (with masterwork mechanisms wherever possible... it's beautiful to see trolls explode into tiny bits and pieces flying every which way).
I build various trapboxes at the corners and sides of the map, with a few animals in the middle, and a spiral walkway to get to them, then build weapon traps around the spiral. This draws ambushers to them, although I have ended up with siege squads stuck there after their commander got killed (I think a larger entrance room with weapon traps before the spiral with some sort of water trap or drawbridge trap to make sure they all die even if their leader dies to the first weapon trap would make sense). I also usually build a secondary entrance protected with cage traps and drawbridges so that my dwarves can go in and out easy without having to path through the long trapped entranceway.
At some of the zigzags I will both other fortifications with ballistae far behind them (unless I end up with some blind dwarves, then I will put the ballistae closer to the fortifications). If I run out of room underground, I will often start extending the entrance above ground. Usually with a raized 1 tile wide switchpack pathway where falling off requires pathing again. A mix of full spiked ball traps, and full axe blade traps are usually enough to encourage dodging and cut them up enough to see them dead.
I know it's not exactly fair to the attackers, but hey, I enjoy watching them get wiped out by traps.