Funny, I start with trains in 1850 and still make loads of money by 1875! Lol
In fact, nearly all attempted cargo routes either break even, or lose money (I use mostly trucks for cargo, trains never make me money!). So I tend to do no cargo until I have a solid passenger base to act as a safety net.
I even over use trains, having more small trains, rather than fewer large ones.
I always start by connecting to easily connectible cities with a double train line, and 2 trains with 4-5 passenger cars
And create a few various bus routes inside each city to supply the stations, with around 15 busses (horses), to start with anyway…
Within a few years that alone makes several million.
Then I just add more cities, but I never have trains going long distances, seems to earn less for me.
If I have 3 cities, A, B and C, I only have a line from A to B, and then a separate line from B to C… Never A-B-C-B.
For some unknown reason, 4 trains running 2 separate lines cost less than 4 trains running to all 3 stops.