Sometimes people might say that "Apostrophe (') " is his most accessible, and in my case, I say it is. So it's good to start there. I happen to find Hot Rats to be a more experienced listen,that you should tackle only after you've heard a couple albums. Same for Lumpy Gravy, that's avant garde. So, I'd say get Apostrophe', We're Only In It For The Money, and Uncle Meat (one of my favorites.) And once you feel good enough to want more, get Weasels Ripped My Flesh, that's my favorite Zappa album thus far.