TOPIC: Mid to late-game tactics?

I usually do ok the first few years, but then when the game starts to get into mid/late-game I always fell off. My trains start to cause traffic jams, I struggle to find new ways to generate cash (usually I build a long nice route from one side to the other, then revert it with good later).

However what do you guys do after this? Remove initial railroad tracks and replace with monorail? Or do you just leave it and start with a new monotrack line? How do you group your trains? Eg. short range trains etc?

In a desert game, you could buy a lumber mill (if you have enough money), and a long route (to a factory). It will cost a lot of money, but it will make even more, because you get very well paid for transporting wood.

You could also try to find the cause of the jams (for me it's often broken trains), and solve it (by placing more depots or changing the service interval).

Good Luck!