You know, I had a difficult time with abbreviations in nursing school. It is just one of those things that you get used to. Repetition. The abbreviations will get easier to understand the more you see them.
Many facilities' medical records departments have an "approved abbreviations" list and only those abbreviations are permitted in charting. In my experience, it has been found in a polices and procedures manual. Also, the med rec dept would probably be glad to print a copy for you if you have trouble locating one.