I would add “Question everything your professors tell you about politics, religion, culture, or anything not math and hard science.” Also try to take classes with visiting professors from foreign countries. Not only will you get a different perspective but it’s harder for those in power to brainwash or intimidate foreigners.
Join the debate team.
If you do so... you will be forced to examine and argue different sides of every issue.
If your kid is a conservative... encourage them to do this and write for the college paper.
If you get crappy grades for equal work from a liberal professor and you are an OUT conservative on campus... you can take your work STRAIGHT to the administration and tell them that you are being victimized for your political views.
(Not that this ever happened to me or anything) ;)