A couple of tips I use personally:-
1) No such thing as redundancy in DF, if you have 1 workshop have 2 dwarfs with the relevant skills enabled, if you have 2 workshops always have 3 to 4 dwarfs with the same skill enabled. You never know when the cheeky little buggers decide to sleep, eat, take a break or worse go pick up a sock.
2) Make sure that each one of your dwarven population have a two or three skill sets instead of specialization, you never know when your super duper Legendary Weaponsmith might die, go insane, berserk or just generally flunk out and you need a replacement.
3) More is better, more food, more drinks, more of everything, always have spares ready just in case.
4) Make sure to settle one level at a time, close the gaps to your fortress and make sure it is secure. The whole danged world is out to get you.
5) Military, never too early to start them. You WILL need them.
Unless you turn off invasion or use Runesmith to smite every creature in sight. 
6) Contrary to belief Elven caravans do not bring better and more tame creatures to sell if you make them happy. They just bring more junk instead.
7) If you have FPS issues do not mess with flowing water or magma.

Make sure you know or remember some of your dwarven population preferences so that you can choose a not so demanding Baron when the time comes.
9) A weak hammerer and sheriff will make your life less miserable.