I'm still learning...my wife and I have been studying sign for at least a couple of years now. We think that the place we started out learning to sign was teaching us PSE, but now we take lessons from a fellow who is an interpreter and very gung-ho about teaching ASL and ASL grammar--which is just the way we want it.
After all, when I went to a class to learn Spanish, the teacher didn't give me Spanish words in English order--I got honest-to-goodness grammatically correct Spanish sentences. They may have been really easy Spanish sentences at first, but they were grammatical; a native speaker would, in the right circumstances, utter any of them and not be laughed at for bad grammar. We wish we'd been taught ASL from the start.
I'm looking forward to the next lesson, because the instructor gave us some questions to try to render in ASL that seem to me to require things we haven't yet learned, so we will be asking lots of questions and, I hope, learning quite a bit. (My questions have to do with how to express chained possessive relationships (e.g. "My father's lawyer's friend's dog has fleas") and how to talk about propositions (e.g. "Joe thinks that unicorns are eating his tomatoes").)