From #openttdcoop wiki
An illustrated guide to proper building
To help our new members and for reference, we have written a number of guides that will help you to understand how our games work. It is recommended that you read them in the order listed below.
Part 1: Basic Stations
First, we will start building a simple station. Before we start we want to make clear that our construction style is expandable in the future. Therefore, we construct huge mainlines and connect sidelines to this mainlines. Stations are ALWAYS connected to sidelines.
Part 2: Basic Junctions
In this part we build the first junction (in #openttdcoop we always call it "hub"). Since we always build multi-track-junctions, a junction is a bit more complicated than it seems at first. Since we want to build efficient and fast railway networks, we need efficient and fast junctions as well. For the start we will analyse a so-called "Side Line Hub" (or "SLH" for short).
Part 3: Mainline Junctions
After building the first hubs in part 2, you will probably notice that our mainlines may sometimes cross each other. Since we always build a comprehensive network and always avoid dead-end lines, there is a point in the game where a so-called "Backbone Hub" is needed.
Part 4: Networking
After being able to build all this nice little hubs we return to some basics. Actually we demand you to do something very important before you start to build: just think about what you are doing. In the ruleset you probably read about our intention to build a comprehensive network. In a typical 512*512 game we have developed a certain networking-style.
Part 5: Trains
Trains are a sensible part of OTTD. On this page, we just intend to make some short statements that help you building them for large networks like #openttdcoop's.
Part 6: Orders
After you built the first trains, you have to think about that. You'll find some guidelines on feeders here as well.
Part 7: How not to build a network
This guide is purely to show what happens when all the coop rules on building are blatantly ignored.