As a new player, here are some tips I figured out that were pulled from several different locations:

General

First, read/go through the openttdcoop tutorial save files. These are some tips in addition to, or repeats of those files.

Look at the map: find the mainline (ML), sidelines (SL), and sideline hubs (SLH) that connect the two. Look at some stations that are connected to the sideline. If there are lots of extra tracks, signals, and a depot that doesn't make sense, go read the articles on overflows at https://wiki.openttdcoop.org/Advanced_Building_Revue.

Your First Station

A good thing to start with is a simple station serving one pick-up (i.e., just coal, just wheat, just livestock, just steel, etc.). You can read the tutorials on stations, but essentially you have to worry about 4 things:

• Where will the platforms go?
  • The number of platforms determines the maximum loading rate, which is almost always faster than the industry production. Therefore, in theory, you really only "need" one (or two) platforms for pick-up stations. Extra platforms really just serves as waiting bays for extra trains.
• How do trains get in?
  • Simply connect to the sideline, and run a line to your station. If you have more than one platform, use signaling (see below).
• Where will the waiting trains go?
  • Pick up stations can have trains waiting for resources to be made. There needs to be somewhere for these trains to wait and not block the sideline traffic. Simplest: just get a long piece of track where trains can queue. What you're more likely to see are overflows. Again, read about overflows at https://wiki.openttdcoop.org/Advanced_Building_Revue. Trains entering a station with an overflow usually follow this logic flow:

1. Is a platform free?
   1. Yes: Go to a platform
   2. No: Enter the overflow. The overflow will have a reverser that will change the train direction. The reverser is just one train-length worth of track that forks in to at least two directions at the end (looks like a chicken's foot or an arrow). It just tricks the pathfinder in to thinking there is a path, then the train hits the end of line and reverses. Why is there a reverser? It hides the depot, which is after the reverser from all trains except those that have gone through the reverser. You can read about it in https://wiki.openttdcoop.org/Advanced_Building_Revue.
2. After the reverser, there will be a depot and then a stretch of track where a train can wait for a free platform, called a waiting bay. Is a train waiting in the waiting bay?
   1. Yes: Go to Depot
   2. No: Go to waiting bay
3. If you are in a depot, you will wait until (A) the waiting bay is empty AND (B) there is no train in the reverser/on the track in front of the depot. This is checked by placing a two-way exit pre-signal in front of the depot facing the reverser. Depots have a built in entry pre-signal, so a red exit pre-signal will keep trains in the depot.
4. If you are in the waiting bay, wait until (A) a platform is free AND (B) no other train is coming towards the station from the sideline. This is done using priority checks (see below).

• How do trains get out?
  • In the end, this is easier - simply join the tracks together - priority doesn't matter, and re-join the sideline.

Signaling and controlling CHOICE/PRIORITY

This is the biggest thing to really learn about! There are several rules scattered over the internet, so here is a summary:

Merging (Load Balancing)

All over the internet, I read about the importance of "load balancing" and "load balancers" -- but couldn't actually find someone saying what that means! The reason: "load balancers" are obsolete because of the approach of "balanced" merges.

Keep signals every 2 squares (that is, signal-blank-signal).

Getting Trains In

Create a connection to the sideline

The network is organized by mainlines (ML),

https://wiki.openttdcoop.org/Advanced_Building_Revue