I'm not very good with chords, e.g. I can never find those really lovely special ones that others find.
Given a guitar and a tune I don't know, I generally try to predict the melody and that prediction gives me an idea of which chord to try. I'm afraid it's hit and miss with me but given a simple melody of a type I am familiar with accompanying, I probably win more than I lose but even with those I can blunder badly. From their on, my approach is to try to analyse my mistakes.
If I know a tune, the prediction element goes and I stand more chance of success, at least to the extent where I would suggest I would find suitable chords for "Wild Rover", "Black Velvet Band", "Sam Hall", etc. first time round.
I do fail dismally on some songs though - even with work I fail to find a suitable chord.