Start with the places, not a transport product
List the places that matter to the trip before choosing a rail pass, flight, bus ticket or ferry. Put them into a geographic order that makes sense for the journey, then decide which stops are essential and which are optional. This keeps a transport product from becoming the reason for an unnecessarily complicated route. A useful plan can be simplified if a connection, a reservation or a change of base becomes less attractive than expected. The right question at this stage is not which product is best in general, but which connections the itinerary actually needs.