If there is a spot to hang a mirror, go for an additional one - besides the one you already have over the sink. Will make it feel less closed in and gives a more expensive look. Also, the mirror you currently have over the sink.. is it large enough? Should you replace it with something more significant? You may want to consider this. Since your bathtub is blue. I would add as much blue accessories as possible to tie it all in - like blue and white plaid towels. You may want to paint the cabinet under the sink the same shade of blue; it will help the toilet/tub not jump out at you

Hi - if you can't replace the wall paint, tiles or the colour of your bathroom suite - then perhaps you might want to jazz it up?

Have a look on this page for some curtains to go in front of your bath tub? Make these in the same colours as your towels - perhaps some pretty pattern in blue and white?

http://money.howstuffworks.com/personal-...

You could also perhaps hang a large mirror above your sink? Or a largish basket with some nice coloured towels rolled up and placed in the basket - use two colours i.e. blue and white or perhaps you might have space for a shelf or two - you could possibly also display towels this way by folding them up and placing them in alternate colours i.e. one white, one blue and then another white and another blue etc.

Also, on a shelf you could place some fragrant candles and bubble bath, bath salts etc and put in some nice bottles to display.

Look at some of the pictures here for a few ideas and inspiration :)

https://www.google.co.uk/search?q=how+to...

Also, have a look at these sites:

http://budgetdecorating.about.com/od/bat...

http://www.bhg.com/bathroom/decorating/d...

http://www.pinterest.com/diyboards/diy-b...

Anyway good luck and hope the above helps :)