Although Clem's primer runs about 45 pages, IMHO a couple of items are missing:
1) If you are married, have a joint checking account, and in the process of building a layout--buying trains, track, scenery, etc--please think of a budget amount you don't plan to exceed. (I would also say this if you were planning on a trip to Las Vegas.) Problem is that it would be easy to drop $10,000+ at York without much effort. I always told my wife what I would be spending, and got agreement from her in advance. Thus when I returned home she did not go into shock or demanded large quantities of gold and diamond jewelry in retaliation. (I am still happily married after 30 years and attended York for 25 of them)
2) If you are a senior, knowing where all the bathrooms are located is vital. The TCA's map you get in the mail has those highlighted. As someone previously mentioned, bring single dollar bills for the bathroom attendants.