Keep your seeds in a seperate stockpile that only allows seeds and turn barrells down to zero with Shift-E.
Reason is that a single barrel holds a LOT of seeds, but when a dwarf goes to grab a seed to store it, instead of doing the logical thing and getting the seed and taking it to the barrel, he grabs the barrel and takes it to the seed, picks up the seed and puts the seed in the barrel, then takes the barrel back to your stockpile.
The entire time this is happening, your farmers are complaining that you don't have any seeds. It doesn't stop the farmers from working, but it does create an enormous amount of spam in your announcements and can make you miss something important, like your boozemaker running out of pots. Of course your boozemaker will simply quit working until you retask him, so you can break your fort by missing that announcement without ever knowing why.
A single 3x3 stockpile is more than enough for plump helmets. I like to keep seperate stockpiles for the important (non dye) plants so I can glance and see what's going on instead of having to check for them every so often. I also seperate the grown food by type instead of clumping it all together, but that's just me.
To store prepared meals (easy, lavish etc) I like to make a seperate stockpile away from the farms and close to the dining room that has everything blocked and prepared foods enabled. (I think it's U for prepared food).
It will help you keep an idea of what your stocks look like if you seperate your booze and your food as well.
Pots are better than barrels for booze. They weigh less and hold more than barrels, and you can make pots from stone so you don't waste wood on food storage.
Turning off invasions is probably not a bad idea for your first few playthoughs. Creating a military is stupidly complex. Like to the extreme. Nothing is more frustrating than your fortress disintegrating around your ears because you spend hours trying to prepare for an invasion and still can't get your marksdwarves to pick up the right ammo (or any ammo at all) or to realize that the squad you have been training for two years hasn't done any training at all and now you have a dozen cave dragons supporting trolls and goblins. Better to bring a mechanic and build traps or lock yourself in, killing the invaders just isn't worth the hassle at the beginning. Not to mention the extensive infrastructure that a good military requires. A large hospital with all the plaster, traction benches, beds, tables, crutches, splints, dedicated medics, a well, soap, buckets...plus the barracks and the furniture they require, keeping the soldiers fed and happy while they train and patrol, making sure they have access to and carry the right equipment..go ahead and make your rangers marksdwarves, you will regret it. Go ahead and make your legendary woodchopper an axedwarf. It all amounts to epic amounts of fail until you really get the hang of a fortress with no military requirements. All it takes is one death on the field to wipe out all the time and effort you put into making the fortress. One death of the husband of a marginally unhappy wife sends her into a tantrum in which she destroys a drawbridge trapping all your dwarves in the wrong place, leading them to increased unhappiness because they get hungry and thirsty or slaughtered, which causes them to tantrum and go insane and start killing everything in sight.....
It's really not worth it.