I think there is an excellent Steam Guide about this. I usually activate only a small number of policies:
- Industry 4.0: Absolute must-have if you have too many educated workers
- Industry filters (mostly for role playing)
- Heavy traffic ban: Wherever it is necessary to redirect heavy traffic
- Foster bike use (or whatever it is called): City wide if I have a good bike network.
Many other policies can either be archived by other means (e.g. just build more parks instead of paying 25% more per park). Or it is completely rubbish, such as smoke detectors which costs much more than just building some fire departments.