Every time I play OpenTTD, I manage to make profit on trains only.
If I play against AI, they start building mostly vehicles and they manage to make profit on them. And I am not able to profit, even if I copy scheme of my AI competitors.
Although at the end of game, I always manage to get above 900 points, I would still like to change my game a bit and use more vehicles.
So: What are common rules to make profit from vehicles?