<p>I would say just start with one or two math classes and see how it goes. The math sequence gets gradually harder and you will know how far you can comfortably go. Courses through linear algebra and multivariable calculus are taken by majors in many different fields, but real analysis and up is mostly for math majors. </p>
<p>Even if you eventually decide that you do not want to complete the minor, a few extra math courses behind your back will only help you in graduate school.</p>