The biggest tip I would give anyone is do your best and be confident in your calls. We had a couple young dudes this weekend that actually did a decent job, but half the time no one knew what the call was. Even balls and strikes was a struggle. I wanted to tell him, "you are going to get yelled at by dumbass parents either way, so just make your call and make it so we all know what it is".
Appeals are always my favorite. For those that don't know, there are only two umps. When someone gets on, the field ump stands behind the pitcher. Its always a big lol when a kid checks his swing and the coach asks for an appeal. The field ump has basically the same view as the home plate up, but he is just further away so an appeal makes no sense anyway. 99.9% of the time, he just agrees with the call. This weekend, the field ump was a crotchety old dude and they appealed to him and he basically said, "eff off, I don't have the angle for that". The home ump was a young kid and was like, ok what evs, guess my call stands. It was a hoot.