I normally wear 6.5 for sandals/pumps and 7 for sneakers/boots. I have wide feet so I ordered 6.5W but those are not wide enough and insoles are slippy. My feet slide to the toe room every steps so my heel side has an empty space. It's hard to walk.
I should've ordered 6W or 6WW if they have them. Those are nice leather pumps for my work so I've been wearing these with non-slip insole. Not perfect but I'll try another size which means I love them.