Frank was a LEGEND.

so do not profess to be an expert on the man... I like Joe's Garage and Zappa In New York.

Of course, The Mothers of Invention (nee, Mothers) were fucking cool - not sure I'd get into Zappa's 80s stuff as much.

"The early Mothers' anarchic stage shows were legendary — during a 1967 performance at the Garrick Theatre in New York, Zappa managed to entice some marines from the audience onto the stage, where they proceeded to dismember a collection of baby dolls, having been told by Zappa to imagine that they were "gook babies"

this is what i'd do (though i'm not a conclusive expert):

The first 3 albums Freak Out, Absolutely Free and We're Only In It For The Money are all works of absolute genius. There was a very reasonably priced boxset of them about a few years ago, though a quick scan of Amazon didn't bring up anything. But they are all supremely good and should be bought in whatever package necessary

i'd then go for His 'jazz fusion' albums Waka Jawaka, Hot Rats and THe Grand Wazoo. They were also available in the same sort of boxset so if you can find that anywhere prepare to thank me profusely.

Other brilliant albums are One Size Fits All (reputedly the most pop Frank got), Roxy & Elsewhere (live album featuring perhaps the greatest Zappa instrumental moment, the combination of the 2 tracks Echnida's Arf and Don't You Ever Wash That Thing), as well as Apostrophe and Overnite Sensation (my first experience of Zappa was a double album with both these on, and i pretty much creamed my pants over it).

There'll be loads more i've missed, but all of these are superb. And i've not really explored his latter career much. But if you can't find the boxsets and can only afford 2, get We're Only In It For The Money and Hot Rats. BELIEVE

its companion piece Overnite Sensation (they even used to be released on one CD together)...

Then Sheik Yerbouti and Hot Rats...