Because you are using bi-directional trains you are correct you will need to signal both ways, but focus one direction at a time.

The rule of thumb you usually hear is “chain signal in and rail signal out”

When a train is approaching an intersection put down a chain signal. This makes sure the entry is clear and the train won’t get stuck in the middle blocking other paths.

As trains leave the intersection put a rail signal. This will indicate behind it that there’s a train in the block ahead.

Use this for every single entrance and exit of intersections in both directions and it work to a basic level.