Size down generally. These are hard for me because I'd be a perfect 36.5 if they had them. Yet I still have 3 pairs despite them not fitting well. The denim/cloth/canvas ones fit larger than the hard plastic materials so you might get away with sizing down a full size in those.
My best binx size is a 37 although in the denim pair I should have gotten a 36.
Some comparisons:
I wear a 37.5 in Celine skates but have a few 38s that work too, but wear 37 in the Celine pull-on tab sneakers.
38 in Isabel Marant Bobbys and 39 in Barts.
36.5 or 37 in Saint Laurent sneakers but 37.5 in their closed boots.
37.5 in Rag and Bone Newburys and Harrows (with a couple 37 Newburys that are suede) but a 37 in any flat sandals.
37 in Chanel Espadrilles
38 in Golden Goose sneakers
I could probably keep going so if I haven't named a shoe you own feel free to ask...