To be fair to OP, the biggest hurdle in learning anything is knowing what questions to ask. When you don't have ontology as part of your vocabulary it's hard to find literature regarding, say, "comparison of ontologies for user-generated text content".

I suppose this flows back into library science, which is all about systematizing where to look for answers to questions, but I'm always astonished to find that there's oceans of literature and research in questions I haven't even thought to ask.