I would definitely want to establish a code of conduct first. You don't want people coming in and breaking something you own because they didn't realize it was not a toy.
Next if you are going to be a club, determine the responsibilities of club members and set up some way to make decisions as a group. Likely you'll either need a leader or some form of board of directors to run a club.
Also important is when and where to have meetings. Typically meetings would be held wherever the layout is, but sometimes they could be at members homes. Its a good idea to work out a good time to have meetings with members that most can attend regularly.
Layout constructions standards of some kind should be followed, especially if you don't want to continually repair or redo mistakes because of sections being built in haste. Plan ahead, make changes to the plan, review the plan again. I'll emphasize that you should always have standards for wiring color. Going back to troubleshoot a bad connection is hard enough with most under layout rats nest wiring, but almost impossible when all the wires are the same color. Also, a "measure twice, cut once" kind of philosophy will save you lots of time and trouble in the future.
Locomotive and car standards should also be in place prior to any kind of running. Operations are especially frustrating when cars are constantly derailing or uncouplers are coming loose. Some good examples of car standards are to have properly weighted cars, metal wheels in the proper gauge, and couplers at the correct height. These are just some basic standards. Some clubs want particular era's and require weathering of cars.
If you do want to run realistic operations you'll want some guidelines established for this as well. Having jobs determined ahead of each op session speeds things up and makes running more enjoyable.
Keep things simple and stick to your standards and everything will run smooth and be enjoyable for most. Don't go overboard with rules because you want things to remain fun.
