I've sort of completed my outside defenses, now. I have a wall running around about half the map. Simply crammed with trees, four layers of soil and a one layer aquifer below that. To the west are wickedly steep cliffs, that run up to a volcano. Stone isn't a problem. I haven't bothered tried to pierce the the aquifer yet. The west side of the map goes straight down to the magma sea, no aquifer.
Oodles of minerals, in a calm environment. I'm still trying to learn how to get things done effectively and wanted a good embark with all the resources easily available. This strategy has worked wonders, I recommend it to other new players, that are frustrated with getting frapped.
Of course, it didn't help that I kept entirely abandoning after every single embark and building a new world. Facepalm stupid right there. On the other hand, idiocy had a side bennie on this occasion. I have this really slow computer, so waiting through world gen was excruciating. Until I started reading the Wiki while I waited...
I have a bunch of 2x3 bridges setup in an eight wide strip running around the outside of the map. Not all the way around there are like 50 z levels of cliffs, lots of channeling. I use the bridges to isolate sieges so that my simple military - which amounts to
"Go kill those goblins! Yes, Urist, without weapons and armor"
{Oh my god! How did they get inside my walls? Must be a dammed bug (Nope they walked out onto your walls from a z-level up and down the track ramp(s!) you conveniantly left for them, but forgot were actually, you know, ramps... Clever goblin bastards...) Why do I keep putting off learning about alerts? }
I've played this embark a lot and my dwarves kept getting getting pincushioned from the cliffs by gobbo ranged attacks. I tried a whole bunch of stuff, a big-ass wall. De-ramping the entire map, (what a pain in the ass that was, stranding dumb ass miners left, right up and down.) Finally I just channeled the edges back until the valley floor was outside of the 20 tile range of archers, and isolate the level at the top. Workes great. Time consuming. Haven't had to deal with flyers yet, except for buzzards. I plan to have everyone run inside... you know once I bother to learn about alerts and burrows...
Anyway the bridges are really cool. Since my military sucketh so badly the bridges allow me to let just a couple of bad guys in at a time. Or simply isolate them in a small section whilst my dwarves run about the rest of the map. Then my wrestlers swarm 'em and punch their skulls right through their brains.
Funny to watch. Especially enjoy the occassonal spray of teeth...
I've got a couple of mist generators, a legendary dining room and everyone gets a nice big room. So I don't really care if dwarves get killed. In fact, too many dwarves is a problem (my sucky computer), so my outside dwarves get poked, prodded, bludgeoned, magmaed, you know... while the inside dwarves eat cake.
All so that I can play with water cannons.