>>34451488You should save Turn A until after you've watched a few Gundam series first. You want some UC and AU Gundams under your belt before you watch Turn A for the maximum impact.
For UC, you start with Mobile Suit Gundam(the original), go on to Zeta Gundam, follow up with ZZ Gundam and finish off with Char's Counterattack. The reason for this is that this story arc is the foundation of UC Gundam and every other UC series builds off of it.
AU Gundams tend to be self-contained and you can watch any series all the way through or start wherever you want.
