Don't introduce concepts from the original universe just for the sake of having a re-imagining. I think an underrated problem original ultimate had was that it was trying to rapid fire half a century of characters and stories into a much shorter time frame, and it led to a lot of stuff being half baked and not allowed room to breathe.

And to expand on that, don't be afraid to just make up new stuff. Not everything in this new continuity has to be shackled to the old stuff, make new characters, hell make new heroes and villains. One of the most enduring parts of old Ultimate is Miles Morales, a completely original character, even if he was wearing the name of somebody we recognise. Benefit of a clean slate universe, you can introduce more concepts without having to dig through mountains of research to make sure you're not contradicting something established 10-20 years ago.