Be as monochromatic as possible! Opt to paint cabinetry similar to the wall color to make it feel less heavy and imposing. Select tile and counter in similar tones. Let's look at these monochromatic bathrooms...
Ok that last photo brings up my next topic, the vanity. An open, airy vanity feels great in a tight bathroom. Pedestal sinks are also a great option, if you have a linen closet or other storage close by. Lastly, if you choose to stick with a traditional cabinet, a furniture looking piece may feel better. Go for smaller legs or feet rather than something heavy and blocky.
Ooh that last pic brought up another good point....the tiled wall is a great way to draw attention to the wall and make it appear larger. Imagine that same bathroom with a small 6" backsplash that is the width of the vanity.....um no, that wouldn't have the same affect as the lovely photo above. A tiled wall can really help fill the space out, just keep it clean.
Next piece of advice is pretty widely known, but just in case you are new to home improvement, open shelves are a fitting addition to the small bathroom.
Photo credits: http://www.manybidets.com/blog/the-colors-make-a-difference/, http://www.styleathome.com/kitchen-and-bath/bathroom/5-fabulous-bathrooms/a/29257/2, http://shoeboxdwelling.com/2014/01/16/minimalist-apartment-in-brussels/#more-12998, http://newlywoodwards.com/2010/08/clean-classic-and-practical-bathroom.html, http://www.lizmarieblog.com/2014/03/favorite-things-fridays/, http://www.shanty-2-chic.com/2014/01/easy-diy-floating-shelves.html, http://thespacebetweenblog.net/2014/09/25/rustic-bathroom/, http://www.styleathome.com/homes/interiors/house-tour-neutral-pale-cottage-retreat/a/56357#ss-9ef32c83-0c08-4fa3-b08d-0ae9d48b5193-slide-11, http://www.arkpad.com.br/referencia/inter_4005-d4689, bhg.com