Well, my current fortress is still in mid fall of the first year, so....
Very Short Term
Get started on the workshop area after the liason leaves....
Once some more dwarfpower arrives in the spring, fully dedicate the miners to the tasks.
Fend off any annoying chasm critters if neccesary.
Short Term
Fully flesh out the bedrooms, dining room, the essentials....
Train up more miners....
whatever else
Mid Term
Do some exploratory mining (I spotted some iron in the northern section of the embark area, and the area looked like it has a good deal of resources)
Prep the magma pipe opening for the building of my megaproject idea.
Discover why there aren't any cave spider webs*....
Experiment with bridges and stuff and attempt to create hand-like motions....
Long Term
Finish my altar to Armok, place the hand thing somehow, above the magma.....
*I have a chasm which fits inside my 6X6 embark area and runs the entire North-South side of the area. It's almost completely exposed to the sky except for a bit of the fan rift (or whatever you call it) at the southern end which sticks into the mountain. While there are alot of chasm critters around, there are still empty spaces where the cave spiders could spawn (not to mention out in the open). I usually have over 50 webs scattered around by the time my first winter arrives.
Edit: update: Gah, I nearly killed one of my own miners due to dwarven stupidity. I was removing some floor tiles (decided to pave the murky pool first and then cieling it, rather than the other way around) and thought I had undesignated it in a way so it wouln't collapse. He now has a brown upper spine wound along with brown upper body, yellow right ear and yellow right upper arm and brown head wound (no brain wound though). I guess he fell on his right side. Anyways, he has the extremely tough attribute, so hopefully he doesn't stay in bed for long.