The most recent episode of Delta did a brief recap of the previous series in chronological order. Basically, the order goes...
Super Dimension Fortress Macross (adapted/modified in the '80s as Robotech: The Macross Saga) --> Macross Plus --> Macross 7 --> Macross Frontier --> Macross Delta
The years each take place, in the same order as above, being...
2009-2012 --> 2040 --> 2045-2046 --> 2059 --> 2067
There's also Macross Zero, which takes place one year before the original SDF series and is referenced through an in-universe movie in Frontier. In regards to the films, they've all been alternate continuity retellings compared to the shows themselves, with the exception of the movie version of Macross Plus vs. its four-part OAV. The movie for SDF, Do You Remember Love?, was acknowledged as another in-universe theatrical version of the events of that show, though at this point, there's the question of how much of it actually applies (Minmay's performance of the title song and its origin, for instance, seem to be acknowledged as canonical at this point in spite of not showing up in the original series). There are two films for Macross Frontier, both of which are extensive revisions of the show's original story.
If you've heard of something called Macross II, feel free to ignore it. It's non-canonical.
My recommendation for now would be to focus on the TV shows, then look into the films if they pique your interest. I'd say watch the OAV for Macross Plus (four episodes, as mentioned, last one to make it out of Japan, with the dub being well worth it for Bryan Cranston alone), then try Macross Frontier (25 episodes). Macross 7 is pretty much the most over-the-top of the series, so YMMV, and has the greatest time investment (49 main episodes and three encore episodes). Macross Delta is still going right now (expected to go for 26 episodes), so catching up with that can wait for now.
tl;dr: I'd say try Plus, then Frontier for now.
