8) Take some small classes with professors who can write recommendations
If you're not interested in graduate school, skip to the next piece of advice. But if a master's or a PhD is an option, you will want at least two or three high-quality recommendations from faculty.
To do this, you'll need good relationships with professors. This means one or two small classes with the same faculty member, and several visits to office hours. Maybe a research or teaching assistant position. Or ask the professor to be your thesis or independent study adviser.
If these topics interest you, see my more detailed advice one recommendation letter requests, on how to write to your professors. My blog also has lots of advice on choosing PhD programs and being successful.