I think that if I were to go back in time and give my freshman college self some good advice, it'd be "work on what you really want". I am still interested in machine learning things, and I was interested in machine learning things when I was a freshman. I think fighting harder for more opportunities would have helped me. Maybe. I think I did a good job of that in a few cases.

But too often there was some sort of implied hoop jumping. Something about needing to do boring stuff first so that I could be better positioned to do the exciting stuff. Except everything snowballs. So when you take on work that you don't like in order to get better at the stuff you do like, you also risk becoming more of (and known as) the sort of person who does the first thing, the thing you don't like.

I think college classes enforce this mindset at least mildly because there is a set of prereqs for each class. But especially with internships and things outside of school, I feel like there were more imagined hoops to jump through then there actually were. Related to all this is stuff about assertiveness / saying what you want, which I guess I still have difficulty with. So I'd probably tell my younger self that no one was probably gonna yell at them for asking for work they found interesting.

Worst case, you just do the boring thing in order to gain more experience and resources. But before that, it seems to pay quite a bit to be more firm about actually working on things you're excited by.