I always go with the following strategy:

• Tons of public transport to ensure that local commute doesn't have to rely on cars. In general, if I start to get the feeling that I need to place a highway in the city to solve the congestion problem, then I look what route is under served by public transport.
  • Buses or trams (if I want to be fancy) for shorter routes, metro for longer distances.
  • Passenger trains for inter-city and longest local transport.
  • Cargo trains in industrial hubs, but careful with those, as they tend to generate a lot of traffic when trucks come and go. I usually do some sort of a traffic sponge (one-way road that leads only to the cargo train station) for trucks to wait without blocking other traffic.
• I use highways sparingly and only for longer distances, like connections between cities. I try to build them outside of the city, so it would also act as a bypass - the cars which are not going into my city but through it won't generate traffic in the city itself this way.