A color temp meter simply helps but is not essential. I recommend using one if creating a printing master neg from something like a Macbeath chart. But for general outdoor shooting, two or three filters
will keep you in the ballpark. I recommend an 81A for general drab overcast situations, and an 81C for
deep shade under blue sky. A light salmon-colored skylight filter is useful for minor warming or cutting
UV at altitude, and might also be useful on your digital camera. Other than that, there's no sense getting too complicated.