If your school offers a course to the effect of Intro to Discrete Mathematics or Logic and Proof in Mathematics, that would be a good one. Some people recommend holding off on such a course until second year (and in fairness, it tends to be difficult), but if you're exposed to that sort of material earlier on, you have more time to adjust to it and then, even if it doesn't go well in your first semester, you'll have plenty of chances to try again before it becomes a major issue.
Also, if you take such a class and it goes well, then in your Spring, you can take some combination of Calc III, Differential Equations, and Linear Algebra (a lot of schools offer a computation-based introductory course). This will give you a very good exposure to foundational math and will be great preparation for your later years.
Other courses I'd recommend would be Physics I and II, assuming your school requires them of math majors as does mine. My school also requires two semesters of computer science classes. If yours does, those would be good first-year classes.
A word of warning, though: don't get all of your gen-ed classes out of the way early. Math is a tough major and as you progress, you'll need to devote more time to your math classes. Try to save some of your easy classes for your last couple years when the math will really get challenging. That way, you lessen the chance of being completely overwhelmed.