Practice, practice, and more practice. It is the only way. People who constantly ask for IDs without doing some of the groundwork first are not helping themselves.
I pulled the legend and took it to the website Identifying Late Roman Bronze Coins and it gave me I. Bummer - I must have missed something.
I also checked it on a website; but, websites can get it wrong. Checking the information on a website by going to the RIC listing myself should help me avoid the problem in the future. I will review it a bit later when I can give it my full attention.