Here are my observations.
– Point to Point is good between towns, but within one a round trip is better it seems.
– Ideally a city line should encompass all land use types, but i found that over long time the industry seems to be not getting many passengers.
– After you set up the train lines between cities the most profitable intracity routes are those that connect residential to the train station and return through commercial (as above the industrial connections do not seem to be getting many people).
– Actually the spaces between the stops can be medium to long (like two intersections) and you should put stops close to pedestrian crossings.
– Up until 1930-ish the Trams are better, but afterwards they fall short of buses.
– Number of stops depends on area you need to cover. There should be as many vehicles on the line so that the travel/wait time is low enough for people to use it.
– I usually start with one line circling in the city and based on how the city grows i either modify the line or add more. Usually both. Do not forget to add some streets where needed. Also, all my lane-carrying streets i modify to the widest possible so that i can achieve highest speed.
– I usually carry my lines through railway station, yes. I do not know if that is the best thing to do, but i noticed that far into the game the intra-city traffic becomes less dependent on your lines because people are simply getting cars.
– Also, far into the game the bus stations (bot medium and large) lose their appeal. As they are capped at 27 and 30 respectively per line, if you train drops 200 people then you may lose as many as 85% of them. Normal bus stops are capped depending on how much space on the sidewalk there is. So if you have several lines, assign each of them a different stop and group the stops together. Alternatively get a VERY large bus station mod, which can handle perhaps more than a hundred people. That’s what i do for my intercity bus connections, but it is very big and it only has one stop so the busses can clog the place. This is not very handy close to the rail stations.