Trial and error I'm afraid.
Or just say 'sod it' and put up with it
I've tinkered for ages with mine; adjusting angles and heights, forward/aft etc. Sometimes, that makes a saddle more comfortable. When I'm trying to get it right, I try to visualise where I want my saddle to be, how I want it to support me - and then try and use that visualisation when making adjustments. And sometimes that visualisation guided me in the purchase of a different type/shape of saddle.
I've found flatter, wider saddles work for me best. Tbh, I discovered that more by chance than design; the stock saddle supplied on my OnOne Pompino being like that. I used that info and bought a Specialized Avatar (?) - that came in different widths.... but it really is one of those personal paths and, as said, other people's recommendations are not necessarily going to solve it for you.
Some bike shops do (or did) loan saddles for you to try.