Something that still helps me is on the odd occasion I actually get to sit in the stands and watch a game is to evaluate what I see from that stand point. I watch the plays happen and I naturally sit there and think I should do this, they were safe/out.what is the actual rule that is being discussed on the field, how would I handle this situation, where should I be when the ball is hit, etc. We all have our own styles of empiring a game but I am open enough to still watch a game, use what I know, and also learn from a different persepctive while watching someone else do what I do. I always see things and say to myself "I like the way they did that better than do" or "He/she needs to do this better". Then you watch the calls, balls, strike, the interaction from the players.
Also I cannot speak for any other organization but the one I am lucky to be a part of but we have 6 meeting every year over the winter. At this point we talk a lot about common sense stuff but also a lot of time on new rules or rules changes. It's an open forum with us and we get tons of questions and scenarios every meeting.
But the biggest help is read the book. Ours is a condensed version now and we have a head trainer that teaches us the basics, always, and also what is new. The big thing for me reading the rules is it gets me out of a lot of trouble on the field when the players start barking at me about rules. Every single player thinks because they are a casual fan of baseball or have played the game of softball THINK they know all the rules. However we all know very very few of them have ever even seen the book let alone read it and been taught by it. Knowledge is power. If you know what the book wants you to know it gives you confidence. No one can remember all the rules and everyone gets the rules wrong from time to time. But when I know for a fact I am right on a little known rule the player is losing their mind on me about my arguing with them gets significantly shorter as I know I am right. If they still think they are right I let them protest but continue the game as fast as possible.
Read the book, watch the game, discuss amongst other umpires and practice.