Advice to someone starting again?

So I’ve hit the point where I really want to return to Mercenaries after a couple of years, but I’m in a different region so starting over (also want to go from the beginning again as that’s the most fun part to me).

Never got too far through, was more on the collecting side of things but was wondering if anyone had some tips/guides for starting up and/or over.

I have seen multiplayer is a bit of a ghost land but PvE is where my heart is at for Mercenaries so that’ll be my primary focus, and the Mythic runs sound interesting as I’ve never done those.

Thanks in advance!