How to use onus?

Could you please clarify how one might effectively utilize the term "onus" in a sentence or conversation? Specifically, in what context is it most appropriate to employ this word, and what connotations does it carry that could help convey a particular message or emphasis? Additionally, are there any common mistakes or misconceptions associated with the use of "onus" that one should be aware of in order to avoid confusion or misinterpretation?