Let's talk a bit more about the make-up of Yiddish: it's mainly German, that much is obvious, but the vocab is heavily twisted and most of the grammatical rules have been abandoned. There's quite a bit of classical Hebrew and English in there too, probably some Russian, Slovak and Polish as well. It's where it came from. And now, where Yiddish has ended up, it has given back: chutzpah, shlep, refusenik, nosh, etc. - all essential Yinglish.Link Discuss (Thanks, Yoz!)
As I said, the dialects vary heavily from region to region. My father's mother says "nit" instead of "nisht", something that has my mother recoiling in disgust. Still, either works. You can chop and change as much as you like, throw bits of your native language in when it works, etc. Sure, people do this with other second languages, but in this case it's a core philosophy of the language.
In other words: There's More Than One Way To Do It. Or, as Perl hackers often say, TMTOWDI.
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.