Profits: never sell raw products. Make stuff with them, like burgers or brandy. They sell handsomely
Oh, I do make more complicate products. At the start, I pause the game and look for the simplest chain, like orange juice or beer or wine and go for it, but if a town wants oranges, fish, milk and meat, I need to feed it and keep the demand line full or the town doesn't grow, right? Especially if there are no other shops. I guess then I need to wait until I am making a profit and then go back to the smaller town and take the financial loss to make it grow.
As for the crashes, the game was fairly well along, but as I kept adding industries and trains, the lag spikes become more and more frequent until the point finally arrived where any kind of building froze the game and the game stuttered about every two minutes. Too bad as I was trying to fill all stores in all the towns. I was grossing around 3 million a month and profit was around half a million, I think. Don't remember as I haven't touched the save game since posting.