>>887264Unupdated image, but hopefully fine.
My friend who's a big Gundam fan said to start with the original Gundam or the movie trilogy compilation of it. After having watched it, I thought it was a good introduction. Sets up the basis for what most titles in the series are all about. From there, you can watch whatever, but going by chronological order with the big TV series might be good, but it's not that big a deal.
