I am not a
tiler, however having spent much time reading various posts after the last few weeks I would say this, purely from common sense, however I have seen people recoommend either way.
I would start by tiling the walls first, for several simple common sense reasons.
1. Any mess you make won't end up those nice new floor tiles you've just laid, or have to worry so much about sheets on the floor.
2. You won't have to wait for the wall tiles to go off before you can walk on them, so you can have a more productive time and get the job done quicker without cutting corners.
My response would be different if you were having to match the wall and floor tiles, setting out is more of a problem then, there are plenty of tips about that in the "New
Tiler" area.
I am sure someone will correct me if I'm wrong. I guess it is somewhat down to what you find easier.