Such as? What's the question?

So is the yellow tile reflected in the mirror about the shade of yellow it is, or is it French's mustard yellow? If it is, that really is a nice soft yellow that should be easy to work with. Is the wall color white or yellow, or both?

White or an extremely light yellow is probably going to be your best bet color-wise unless you have a favor color you want to go with. Something like a dark blue would be nice with the yellow but it might overwhelm the bathroom making it feel like a cave.

Find a cute print Roman shade with your yellow in it. I'd go with a print to bring some interest to the room.

The other thing I'd do, and I don't know if this is possible, but I'd try to take that vent cover off and clean it good. I know in old houses they get that way, but if there's any way it can be removed and cleaned, it would help freshen up the look of the room.

My Houzz: Duplex Becomes a Bright and Spacious Single-Family Home · More Info

Something like this would look great

i just finished this bathroom