Goddam Gundam

Having never, ever, read any Gundams I'm lost about all the different series.  Which series is which, are they in a timeline?    Which would you reccommend reading first?

Don't bother with Zeta or Double Zeta, they're both shit.
Gundam-tards will tell you Zeta is greatest thing since sliced bread, but really it's pretty terrible.  Nothing about it is new or original, and the "newtype powers" toward the end are ridiculously lame.