I'm trying to figure out how to decorate my bathroom.

It's tiny. The floor is grey and white. The walls are white. I have a shower/bathtub, a toilet and a sink with no storage or anything underneath. Just the sink and the metal poles or whatever they're called. I have a tiny medicine cabinet that is missing one of the sliding mirrored doors. The lighting is the kind that is under a plastic-like cover over the cabinet. That's about it. It's very tiny. After the toilet, sink and bathtub, there is about enough room for two people to stand in it and not move. Oh, the only other thing is the 2 metal towel racks and my door is brown.

Here's what I'm asking:

How can I decorate this very inexpensively? I cannot paint or put anything permanent on the walls.

What can I do for storage?

Can I get a replacement glass door for the little medicine cabinet? Should I buy two new ones? How do I go about this?

What color schemes would you suggest? Details welcome!!