Studying the skill table, I can conclude that there are 6 kinds of careers to pursue, and 6 main skill sets. I'll list them here.
The BFF to Animals- Career as an farmer that only does the animal side of farming.
Skill set: AK1 to 7, HK, AH and RHK.
Reqs: A house (or superior knowledge to get to animal populated areas), egg seasoner, Some food acquired through vendors, an Animal goods vendor to buy from and a lot of animals.
Job des: Sell milk, meat and grain(now unavailable to gardeners), by products of milk (butter, cheese, etc) and other stuff to cooks. Sell baby animals, hog tied piggies, and eggs.
The Resource Gatherer- Career as someone who just picks stuff off trees and other things to sell.
Skill set: SA skills, LGT skills, JH and BS.
Reqs: Several bags to drag your stuff around with. A house for extra plots. Extensive knowledge of physical features of every street.
Job Des: Sell cherries, allspice, beans, eggs (all in high demand from cooks) and gas, as well as papers. Sell loam, earth, peat and jellisacs. Sell guano off the floor. Also, goodies pop up from trees occasionally. Can in fact, go for cooking skills after completing skill tree. There's not many skills to learn.
The Gardener- Tend crops like crazy
Skill set: Gardening and Cropperry, as well as Botany(If you want to plant trees. Actually, it's kind of a grey area, whether Botany is a Gatherer skill or a Gardener skill)
To be continued.