As of this writing, SUNY-Binghamton has about 450 math majors and 3 professors assigned to undergraduate advising. These web pages are my attempt to offer advice to interested undergraduate students who will not get an in-person appointment. The views expressed here are my opinions, and not endorsed by the department as a whole, much less Harpur College or the SUNY system.
An index of these advising pages is here.
This is by far the most common question an undergraduate advisor gets. The short answer is that you should take Math 330 as soon as possible if you are in pure mathematics, and Math 447 as soon as possible if you are in applied mathematics. If you have not taken the prerequisites for these courses, then do that first. These courses are representative of things to come. If you are planning on pure mathematics, and can't stand Math 330, you may need to think about a new major. Likewise with Math 447 and actuarial sciences. The requirements for either course are fairly modest. Math 330, for example, requires only two semesters of calculus.
Of course you are still asking "What course should I take next?". But I'm not going to answer the question. Instead I'm going to ask you a question, which will help you figure out the answer.
Of course you don't have enough information to know. But often you have to make decisions before you are fully informed. This is one of those times. The answer to, "what course should I take?", is "Take the course that prepares you for your planned career."
Below I will list a few options that may serve as reasonable proxies for what you want to do. But before you click, let me explain why I am doing this. Obviously the idea is a kind of backwards induction, wherein you will ask yourself what you have to be doing 4 years from now to be prepared for 5 years from now, and eventually arrive at what you have to be doing today. But there is a reason we need to do the backwards induction, namely:
The BA-level majors in Mathematics or Actuarial Sciences have minimal requirements. This situation may change, but in the meantime it is important to note that graduating with only the minimum requirements for the BA is not an adequate preparation for most careers. In fact, even graduating with a BS may not be adequate preparation for your planned career, although this depends on what the career is. This can be seen as a good thing, because it gives you the freedom to prepare for a wide variety of careers under the umbrella of the math major. (It also gives you the freedom to goof off, which might not be so positive.)
With that in mind, here are a few types of answer to the earlier question:
Going to graduate school and getting a PhD.
Making money, perhaps by working in finance or as a software developer.
Making the world a better place!
Teaching (presumably mathematics at the secondary school level).
Working in the corporate world. (Whether as an actuary, financial professional, software developer at a startup, or whatever.)
Managing my own record label (or artisanal goat cheese shop, art gallery, bistro, etc.).