"One thing to note is that there is no universally agreed upon convention for denoting math objects."

This is the thing that trips me up most often. It's especially a problem when the author believes that their notation and variables are universal and therefore don't need to be defined. I've spent a lot of time these past few months trying to "reverse engineer" calculations done in research papers to verify their notation.

Textbooks and theses generally do a better job of defining everything because they aren't as concerned about document length.