What are the skills and knowledge you could actually bring & fully realize at some point in the past?
And we're taking this in the strictest, nerdiest, materialist lense. I don't care how smart you are you ain't making a steam engine the in bronze age, for instance.
So what could you create, with just your knowledge & period tools? What kind of institutional, technological, philosophical innovations could you realistically recreate? How would you interface with the social fabric of society to not be some crazed pariah who never positively influences the place they went?
I don't know how true this is but I think a lot of seafaring cultures didn't understand how you can sail into the wind (tacking). I mean you could probably go back in time thousands of years and show folks how to add a keel and how to point your sail correctly, no real "tech" needed.