What are the prerequisites for getting married according to halachah in terms of income and job security?
The Rambam in הלכות דעות פרק ה says the following:
"The behavior of intelligent people is to first get [trained in] a job so he can support himself, then buy a house and only then get married. "
This - says the Rambam - is the reason for the order in the Psukim:
[The following are sent home from the war front]: the one who planted a vineyard, the one who built a new house - and finally the one who got betrothed.
The Rambam then continues:
"But the stupid people, first they get married, then - if they can afford it - they buy a house, and then - later on in life - they try find a profession, or rely on charity".
This - the Rambam says - is hinted to in the Psukin of the curses:
I.e. your approach will be backwards, so that you don't succeed.
The Rambam ends with King David's approach for which he was praised:
(This is one of about 10 times the Rambam calls somebody a טיפש.)
This law is commonly known as שאר כסות ועונה.
Ramba"m seems to disagree with the mishnah in Pirkei Avot (Chapters of the fathers) Chapter 5, mishna 23: