How can I prepare during undergrad for gradschool for CS?

It is quite premature to plan all of this out. In your first year at SUNY, you will get to know the faculty who will be able to advise you on what to do in order to achieve your long-term goals. If you ask them about volunteering in their research groups, you will gain the experience that you need to decide if graduate school is what you really should pursue immediately after graduation.