With Swiss generelly speaking you never get free upgrades unless the flight is overbooked and operational upgrading is necessary. In this case it goes by status, which means circle first, then gold and finally travelclub - after that any other QG member that seems to especially deserve it in the eyes of the gate agent. Sometimes handicapped people or overweight folks are upgraded for free, but very seldom.
Other than that you have to use miles, which is very easy since you can do it last minute at the gate or even onboard. As Travelclub you are able to use miles to upgrade at the gate or onboard from C to F.