I'll toss in my two cents. I think everyone left off one of the most important things...HAVE FUN.
God, if you don't enjoy what you are doing (don't care if it your vocation or advocation) for Pete's sake quit. Life is way to short to be doing things you don't enjoy.
I will study the rules, work on game management, complete the proper paperwork for my association and the state, etc. I'll even send in the paperwork to get paid...but won't call and check the status of the payment. I do this because I enjoy it. Any money is a bonus. I don't worry about tracking mileage, meals and the small stuff (I will keep the receipts for thing over $50). If I was that concerned over the money and advancing I would have started much younger. The way I look at it, the kids in grades 5-8 need someone to call their games as well. If you want to focus on the bigger students so you can advance to the next level that's great, I'll take your rejects.
If this approach makes me a bad official, oh well...someone has the be the worse at every vocation and advocation.