Hello,
I have a half a million population city with around 9000 people that use public transport.
My best suggestion is to plan ahead and take the game slow. You might even try to go vanilla way and unlock all progression milestones. This way you have an organic look on the city. My greatest suggestion is to build independent neighbourhoods connected through highways and not expand existing ones because doing this will wreck traffic flow in the future.
Also the whole progression milestones get your city to around 90k people. From that point onwards you can unlock the 25 tile mod.
I plan my new neighbourhoods ahead. I pick the spot, maybe from the main highway, through a roundabout, which I use as a connection point for the new neighbourhood. The thing here is to use the main highways as traffic collectors and distributions.
When building a new neighbourhood, I start from the center, build all services in a single point - fire, schools, police, medical and most importantly the center of the public transport. For a 20-30-40k people neighbourhood you might need 4-5 or more kindergartens, 2-3 schools and 1 university. I usually plan 30-50k neighbourhoods because this way I can fit all major services and still be on + when it comes to income. For smaller neighbourhoods it is enough for 2 kindergartens, 1 school, 1 small police and fire station.
Always have 2 transportation infrastructure in place. One for the neighbourhood with bus/trams and one outside connection line, maybe a metro to the city center, where usually the commercial and special buildings reside.
Most neighbourhoods I plan are somewhat concetrical, meaning I have that services in center with a bit of generic commercial zone, a ring or more of high density residential and office zones at the outer rings. Think of it like the Nine men morris game.
If you want to see some detailed neighbourhoods you can check my profile page.
I have my half a million population city CSL map in a post along with many videos of different zones in the city.
https://www.reddit.com/r/CitiesSkyl...alf_a_million_population_city_still_got_some/
Also you can visit my YouTube page and find some inspiration there as well.
https://www.youtube.com/channel/UCeVA-2I_mDOg5DLmcviDIWA?view_as=subscriber
The biggest challenge was to keep traffic in check and most of the time I spent building the city was in improving existing conditions and plan new areas.
I have tried multiple ways to keep traffic flowing in very large industrial areas as well as keeping them properly connected to the city. The current traffic flow is 90%.
My half a million pop city has more than 20 or 30 distinct neighbourhoods which all work independently from each other and every new one I plan was better then the previous because I learned from them.
Here is a timelapse of one of busiest central transportation hubs of my city:
Also here is a video showing how I used many metro lines to animate a park with thousands of people:
In conclusion you can use public transport not only to carry people around but also to make some satisfying visual areas of the city.
Also, it's best just to stick to a city and grow it.
Try out new expansion zones differently every time and see how they work out. If you do not like a new area or it doesn't work, plan next one with what doesn't work in mind, but always keep what you have, the map is big enough for every experiment.
Also, try to keep industrial and specialized commercial areas as distict zones in the city and try to keep them well connected to the rest of the city. This way you can improve traffic flow.
Thanks!