Definitely learn to think vertical. I plan out my fortress around a central 3x3 staircase and try and keep things symmetrical and blocky. It might not be super creative (that comes later in Megaprojects) but it helps keep things under control.
Thanks for that, but do you dig into the mountain or dig straight down? Also how wide are your corridors? Finally, do you dig a smaller fort first?
Generally, I find a good spot and dig straight down, build walls and stuff around the entrance up top. I usually just have place my dig designator in the center of the staircase, hit shift+right two times, shift+up two times, then designate shift+down 4, shift+left 4 times. This is for storage and workshops. My living quarters are generally the same size, but I only dig out 1 tile wide halls and then make 4 rooms in each quadrant of the square.
I've been thinking of expanding any and all halls to 3 tiles to alleviate traffic and FPS woes.