A few people have asked about this sort of thing over the summer, and it suddenly occurred to me I'd never seen anything written down, really.
It just seems to be something we pick up from going on runs with others, particularly if they're from the biker community. There's not really a right or a wrong, and somethings change depending on group size. However, there are a few key points there work well regardless.
make sure every one knows which the lead car is for any leg of the run, and that if overtaking (between Westfields) is practiced, (not really a good idea, see next point), that no one is to overtake the lead car. You change leads at halts only. every car is to maintain visual contact with the car behind there will be times when you temporarily loose sight of them, then slow until they catch up. Regardless, when you come to the next turn, you must wait wherever it is safe to do so, where you can be seen by the car behind you, until they catch up. Once the car behind has reached you, you should be able to catch the group ahead up, as they have all slowed once you went missing! If the car behind you doesn't appear after five minutes or so, hang on where you are, as the group ahead of you will see you missing too, and come back either as a group, or just a search party to see if you have a problem, at which point you can go back and search for the car behind you. - this is why overtaking each other is bad sometimes, it's hard to keep track of the car your following and make sure you've still got the right car behind! if the car ahead has a problem and has to pull over, then everyone behind them should pull over too, so that the cars ahead will realise and come back. There may be nothing anyone else can do, but this allows the group to reform and get back into the buddy convoy. Likewise, if you'll be leaving the group during one leg of the run, make sure the leader of that leg, at least, knows, and that when you peel off, you make sure the car ahead and behind realise what you're doing. There's nothing worse than sitting in a lay by waiting for someone that's actually gone home! Equally, there's nothing worse, especially for newbies or inexperienced members than suddenly finding themselves on their own in a strange place with everyone else disappearing off over the horizon. on long runs, it's a good idea to have prearranged stopping points where the group can reassemble if it gets separated. (This doesn't mean stopping for a brew necessarily, it might just be a handy petrol station to pull over at while everyone catches up.) If you have a really big group, say a dozen or more cars, consider having more than one leader and several small groups, with each leader having a map/sat nav/route guide etc Swap phone numbers before starting big runs!
Thats the main stuff really, there are all sorts of refinements, from two way radios o giving out road books, but if everyone practices the basic "keep sight of your buddy behind" technique, everyone should be able to enjoy themselves without stressing over getting lost.