I created my first fortress following those tutorials on the internet. Things went smooth, but since I was learning, things took time, and eventually, the first goblin siege happened. I sent 6 military dwarfs I just began to train, and of course, they were all dead in 5 seconds.
My second fortress went better, as I did things faster, so I could spend more time on the military. I defeated 2 goblin ambushes, with 2-3 dwarven casualties everytime. Things were looking bright, until...
A ful blown goblin siege. With cave crocodiles, trolls, goblin captains and everything. I quickly sent the civiliand to the bunker and sent all 28 dwarves that I trained (bunches of 5 specialized in different weapons, 10 archers). And I basically got a whole lot of fun, as all of them died a horrible way, with my dwarves just scratching some goblins, failing at trolls, always missing beasts, etc. After the military got killed, the siege went in and killed most of my men, and then they went away and the siege ended, and I was left with ~30 dwarves. As soon as I thought I could rebuild, 4 trolls I captured in wooden cages broke out. Lots of fun happened.
Also, my fortress was carved sideways into a mountain, first floor was farming, second was storage, third was meeting hall and beds, fourth was barracks, fifth was workshops, and then there were 4 floors I just mined away for minerals. Also there was a "ceiling" floor that ended up in a cliff, thats where I trained my archers.
So, my question is, what did I do wrong? What should I focus on my next fortress to get greater doses of fun?
Any help is appreciated.