To succeed in STEM one needs aptitude, persistence, and resilience. It helps to learn to work in a study group with like-minded individuals. One needs to develop study skills and the ability to calm oneself during exams. It helps if you can find summer employment in your desired field. This tends to open other opportunities.
Those are great additions as well. The summer employment or paid intern programs help many to continue on their path or find that they should be elsewhere.
For those who are not STEM, and if not going into a trade, my recommendation would be be business major, or economics plus a foreign language to a level of fluency. Study abroad for a year to increase that fluency. Many college study abroad programs today are actually “college vacation” programs run by the student’s university. What I mean by study abroad is where one matriculates full-time in a foreign university program for a full year where the credits are earned toward degree. Also, there is no reason a STEM major could not do the same with language and study abroad. And doing these things one can see with the aptitude, attitude, persistence, discipline, and being with like-minded ... there really is no time to sit around with leftists who are recruiting, indoctrinating, smoking pot, painting signs for protesting, skipping leftist humanities etc.