Oh dang what a different world that you all live in... Eventing, dressage and H/J shows are vastly different from ranch/western/other shows. The only time I've seen everyone going the same way is in-ring schooling for giant indoor shows like the Maclay finals.
If it's an English type show there really are a very few basic rules people are taught:
Left shoulder to left shoulder ALWAYS. Unless one party is on approach to a jumping obstacle from the rail, then they have right of way.
If you don't follow this expect people to get rude, or trainers to yell at you. That's how I learned the hard way when I was a tween - got screamed at a few times, then I was good. Seriously, Left to Left is god, please follow it.
As said above, those jumping have immediate right of way. Don't cross in front of jumps at all cost with your experience level of warm up rings. You could end up in a dangerous situation for yourself and others.
Don't cross in between jumps unless it is very clear and others aren't actively jumping/setting the jump. It's a small area and even for a pony not enough room to get out of the way of a kick.
Riders can ride in any direction they please. They can do circles, lateral movements, halts etc anywhere. It is your responsibility as another rider to handle this controlled chaos and know how to ride your horse in and around it.
I typically halt in front of the jump if I need to discuss something with my trainer so I'm not in the flow of other traffic for the others using the other two jumps, but if you're going to work on the halt, I'd say stick to the rail so others can ride around you. (the one instance I wouldn't go directly to left to left).
Put a red ribbon in your horse's tail. I don't care if it hasn't struck out at someone in 10 years, it's your job to protect yourself and others. I know in a crowded schooling ring I'd get close to regular horses but give anything with red on it a wide berth just for my safety and theirs. Others I expect to be well schooled horses capable of being in the warm up ring presented at that show - or at least have a trainer looking out for them.
This is what a crowded warm up ring looks like - yours I'm sure won't be any near as hectic or serious, but still it'll give you a feel of what an English ring is like. https://www.youtube.com/watch?v=tXO2XhunuuA