What do we learn from "Hachen ba'Chutz Melachtecha v'Atedah ba'Sadeh Lach Achar u'Vanisa Veisecha"?
Sotah 44a #1: "Prepare your work outside" refers to a house. "Prepare a field for the future" is a vineyard. "Afterwards, build your house" is a wife. This teaches proper conduct, that one should first build a house and plant a vineyard, and then be Mekadesh a woman 1 . Also the Torah said "who built... who planted... who was Mekadesh"
Rashi citing Sotah 44a #2: "Prepare your work outside" is (learning) written Torah. "Prepare a field for the future" is Mishnah. "Afterwards, build your house" is Gemara.
Malbim citing Sotah 44a #3: "Prepare your work outside" is written Torah and Mishnah. "Prepare a field for the future" is Gemara. "Afterwards, build your house" are good deeds.
Sotah 44a #4: "Prepare your work outside" is written Torah, Mishnah and Gemara. "Prepare a field for the future" are good deeds. "Afterwards, build your house" - expound in Torah and receive reward.
Rashi: First buy fields and vineyards. V'Atedah is an expression of Asid (the future) - put animals in the field. Afterwards, take a wife.
Malbim: If you want to marry and father children, it is proper to first prepare the means to finance them. Prepare your work outside the house, and prepare the field for the future - you will have a seeded grain field ready to give bread to your house. If you build your house beforehand, you will need [to take from] people, or steal, or be idle from Torah. This is a metaphor - for every end, one must prepare means.
