I wrote a whole detailed post on embark profiles that now I won't be able to use because you asked about trade agreements.
So my actual answer will be shorter, but interestingly, pretty similar in actual objects.
I ask for massive amounts of cheap raw materials, some of them because of rarity but some just because it's easier to buy them than wait around on a smelter and all but free. So it's whatever I'm missing but want. The only expensive raw materials I get are after having squandered all mine or shown up in an embark lacking something critical, like flux or iron ore.
I also usually have a list of instruments and parts I need (if people in the tavern are "simulating" an instrument they will play that instrument if you get one for them and store it in the tavern). These are usually expensive to buy so it's often better to build them internally but if you find that whole process incredibly annoying, it's worth a shot if you have tons of spiked bronze balls and other game-breakingly profitable stuff, or even if you don't exploit to that extent, high quality weapons but made of cheap metals are really good export goods.
I also usually just buy all the food, but rarely request anything unless a dwarf has a preference.
Similarly, I request all metal ores I'm not drowning in. I'll buy bars if I have to but I am generally not buying nonsense like platinum bars. There's also relatively rare ore like bismuthinite that you might have a couple veins in a 3x3 embark. Cassiterite if I'm not drowning in it. Tetrahedrite too but I usually am drowning in that junk. Oddball substances some dwarf prefers. Stone of unusual colors I can use for bridges and mechanisms to color code my levers and what they move. I always bump seeds up a notch or two, not all the way to high priority. Somehow even with seedwatch I somehow run out of seeds.
After that it really depends on specific needs. A lot of these kinds of orders are recurring because I want as much steel, for instance, as I can practically get. I always want food and drink if there's some disaster. My almost never requests are things like gems, originals of books I don't care about, extremely expensive instruments, high quality steel weapons (that I can make better anyway), same with armor
Damn thanks, that's much more indepth than I was expecting at all, but I'll definitely keep these in mind for later. You should def make that embark profiles post anyway, why can't you do it anymore?