you can either go for darker grey tiles or a beige. It all depends on how grey your wall tiles are and if they have any underlying colours - are they are purple or green grey etc etc. How does the ventilator affect the look. Do you have a photo?

You can use natural stone like marble for floor but do not use granite for floor at all as it is very slippery when wet. As for tiles do not go for glazed vitrified tiles for the floor for the same reason. ( floor becomes slippery once wet and may cause mishap) Go for ceramic anti skid tiles that are specially meant for bathroom floor. For wall tiles you can use whatever you like and then decide over the matching anti skid floor tile/ marble. Double charged vitrified tiles are usually used for flooring in rest of the house.

antislip and easy maintainance tiles for exterior is the key. choose any shade, colour, size. must not have deep textures as that's gonna be tough later in use. do consider slope and drainage appropriately as terrace may lead to water proofing issues in future. make sure skirting is everywhere and corners with top part of the balcony wall is tiled properly. thanks shradha shah beescheese design

firstly complete wall putty inside, then flooring, door frames, at last paint