Staying in touch with bankers

Hello all,
I have reached out and completed a few dozen networking calls. I wouldn't consider many of them complete successes, as I don't think they will remember me if I follow up now (6 months later). I want to keep the conversation going, and everyone I speak with recommends that I follow up with updates. But what exactly does this look like? I've begun some modeling courses and am starting an internship soon - are these worthy of an email? Do I ask to speak again on the phone?

(I am a freshman/rising sophomore at a somewhat recognizable non-target).

Thanks