For one, deport the millions of illegal immigrants.
As wells prohibite illegal immigrants from being able to buy houses, as well as even getting a loan for one.
Part of the problem with housing is where. If you are trying to buy a house in popular places like LA or San Francisco, Chicago, New York its going to be extremely challenging. Encouraging buying some place with much lower cost of living as well as cheaper houses. Of course that requires jobs to be in the cheaper areas, figure out how to get more jobs in such areas.
Keep private equity companies like blackstone from owing and buying single family homes. Such is creating a rental trap.