as a rule of thumb, printing filters are only for altering overall print contrast.
If you want to alter the relative colour/shades of grey in the subject then you must use filters when taking the photo. In this scenario any colour filter will allow its own colour through and stop other colours in varying degrees.
So for example, a red filter would darken everything in the subject except for red, creating the impression that reds were lighter compared to everything else. i.e. They change contrast selectively based on the subject colours and the filter color.
This is different from enlarger filters which only change overall contrast. (there is no colour in the negative to change selectively by filter).
The basics of filters for B+W film are that yellow increases contrast a little by removing some blue from the subject (darkens blues a little).
Orange filters do the same but more so.
Red filters do the same but even more and darken greens and blues.
Green filters darken reds
Blue filters are good for showing fog but I'd stick to yellow, orange and red to start with.
Note there is a lot of cyan/blue light in shadows and indirect sky light. Clouds are full of it, so much so that even a light yellow filter will show more contrast in clouds than without the filter.
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