I've spent a fair amount of time trying to sort through this subject.
I use a light yellow filter most of the time (K2 I think) and it usually gives "realistic" results, overcoming B+W film's oversensitivity to blue light. I habitually use FP4, by the way.
I also carry O2 and yellow-green, and skylight filters, and use them sometimes.
The Orange filter gives me some latitude to get a little tone out of blue sky when exposing for the shaded side of a subject. I find the effect overpowering when exposing for the sunlit side of a subject, though.
The yellow-green filter may be replacing the yellow for me, here's why. Its effect on sky tones is almost the same as the yellow, but it lightens deep green colored foliage. Many times I feel the yellow filter tends to render evergreen trees too dark, they look sinister.
On overcast days I often use the clear filter for a little extra speed and since gray skies render about the same regardless of filter color.
One more observation- longer lenses tend to "need" stronger filtration than wide ones. Using the orange filter on very short lenses will usually give very dramatic effects, not my taste, so I never use that with lenses that give a perspective wider than 28mm or 35mm equivalent.
One last note- I cut my medium format teeth with a Mamiya c330 and 55, 80, and 135mm lenses. I found that using a hood is imperative to avoid flare problems, especially with the 55mm. I scrapped my step up rings (nearly all my gear uses 49mm too) and bought 46mm ones and factory hoods. I feel it was worth the expense and extra stuff to carry around.
I hope this proves useful.