To get lots of passengers I create 3 routes from just outside the town to stops in teh 3 zones. As soon as I can I put trams on the route. I then link two towns with a tram route. By keeping teh external link on teh outskirts of my towns I generate internal traffic as passengers want to cross to the shops and jobs. If the town is large enough I separate the 3 routes to feed traffic to a station on the edge of their zone.

Once the trams are overwhelmed with customers I link the towns with a train. Tram profits often stay quite high despite the trains.

On rivers I place a bus stop near the Dock. This stop is served by one route that crosses my other internal routes.

Just adding 1 tram to each zone can easily generate growth and soon my Ferries and trains are enjoying nearly full loads.

More passengers will pay to travel on more routes. eg in one town I placed a Dock next to a station and linked that station to a landlocked town further inland. Soon I had passengers from both towns using the Ferry to travel to another town's shops and jobs. This generated a lot of growth in all 3 towns = more passengers needing more transport :D