If you have passengers piling up at a station, especially a hub station, hit the + button next to the number and sort by "via" first. Usually it will be a single route that's causing the backup. E.g. you'll have 4000 passengers waiting, 3500 of them want to go via Predchurch.
So just increase the number of or capacity of the trains/boats etc running on the line to Predchurch (making sure to avoid bunching and not exceeding line's max capacity).
Another pointer is to avoid over-reliance on hubs. In a network with a single, central hub, the load on that hub (and on the last sections of track before it) are huge, and towns that are close together but not on the same train line take a long time to get between. The solution is to start to provide lines that skip the hub and provide shortcuts You can also just avoid hubs from the start. Depending on the topology of your map, you should aim to have criss-crossing lines, avoiding excessive hubs. Lines should be as straight and direct as possible, and where two different lines meet, they share a station. Look at how my cargodist games end up: https://i.imgur.com/PxxlGw0.png
There's no centre to my network, a few stations where 3 lines meet, lots of stations where 2 lines meet. The network is like a grid, but not too perfect, it just comes from attempting to build straight, logical lines to connect towns that are are lined up nicely.