@Juliette, what cae says is right, I expect it's a lack of peasants that is your problem. i personally always make certain to have many peasants wworking at once, usually about half my population.
another thing to considder is that the peasants also do a diverse range of things, they grind flour if you have a mill, they spin fir into yarn if you have a textile, not to mention transporting everything! so the more activities your doing the more peasants you will need, indeed even while bakers, weavers, builders, farmers and some other jobs all will be peasants half the time, I would also recommend making certain you keep your numbers of full time peasants up.
@nocturnus, As to stratogy with food, I don't believe it's actually the case that your population will starve if they have only one food source so long as you have enough of that source in the tavern being served by your cook, they will also get less work done and need to eat more often. Each food source basically serves as an individual battery, and your population will get hungry and require more food when all batteries are low, so the more batteries you can keep filling the better.
I personally always do basic meat production (ie hunter and fisherman but no butcher), then building materials (ie saw mill and stone quarry)vegies, then bread, then worry about mines, butchers shops and textiles, then wine production last.
this means for most of the time I'll have three food sources available, but also means by the time I start bread making I've got enough of a population to have more peasants doing the increased work.
Also remember that in terms of farming, one farm produces quite a lot, and for a good while the best way to increase yield from one farm is assigning another farmer rather than building another farm.
Of course though, all of this is very individualized, and you might find other ways by experimenting. I for instance never bother with two cooks myself, since it always seems a waste of a usefull person to me, I just instantly reassign a cook if one is injured and always make certain my cook is a man so that they won't get pregnant, (castaways is amusingly one instance where you don't! want women in the kitchin at all), :d..
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