My friend Steve Stockdale, former Executive Director of the Institute of General Semantics (2004 through 2007) has been involved in developing this online course: "General Semantics: An Approach to Effective Language Behavior" For that reason alone, I feel confident in recommending it to anyone who wants to try an online course and would like a structured introduction to the subject.
I say this despite my qualms about the course's focus on language behavior here, which I consider too narrow and therefore potentially confusing if you want to develop a comprehensive understanding of Korzybski's work. Because I see GS as a value-infused, applied study of human evaluation/epistemology (how we know what we know) and a non-aristotelian foundation for the human sciences, I would not describe 'general semantics' as this course description does.
I have come to this view, because such a focus on 'language' by people like S. I. Hayakawa, has historically misled students into neglecting a great deal of Korzybski's work that doesn't fit into the 'language studies' box. However, the radically inter-disciplinary nature of 'general semantics' has traditionally made it difficult to classify it in terms of traditional academic boxes. So here we are. It's an old story.
That said, we surely can't leave 'language' out of the picture. As Korzybskian scholar and former Executive Editor of the General Semantics Bulletin, Jim French has written: "As a field of study, general semantics is not predominantly about language but (one might say) about neuro-evaluating; and yet language and how we use it play a prominent role in apprehending and using the discipline." ("Editor's Essay 2001, General Semantics Bulletin, 65-68, p. 8-10)