Help with my Keyline! Trying to determine my keypoints and keylines on my farmland (goat farm)

Hello! I am looking at implementing keyline design on my fields. I will upload a map of the contour lines and water flow on the land. It's a goat farm with permanent pasture on field 16 and rotating temporary grassland and cereal crops on fields 27 and 28. These fields have the main problems areas and have been experiencing issues with waterlogging in the South East corners on fields 16 and 27, 28 and also the South West corner on field 28.  
Id like to change my tilling in line with keyline design to help distribute water flow and prevent erosion... currently i till up and downslope. There are ditches along the border between field 16 and 27 and 27 and 28. My idea is to do keyline tillage and perhaps keyline subsoiling to help more even distribution of water. With climate change the precipitation is becoming much more erratic....

I'm struggling a fair bit to determine the best keylines for tillage and subsoiling and cropping.

Thanks so much in advance!

Heres another useful image of water flow