Great tips by @Matt Grum, and I'll add that if you have a Canon, your camera may have an "**Highlight Tone Priority**" option that you can enable in the menus. Metering is tricky when a scene is very bright (snow, wedding dress). This option can help prevent blowing out the highlights in very bright areas. According to Canon: "*Highlight Tone Priority mode gives wedding and landscape photographers the option to boost dynamic range for highlights when shooting above ISO 200 – reproducing more tonal detail from wedding dresses, clouds and other light colored objects...*". It is said to provide up to an extra stop of dynamic range in the highlight region.

Check more info and before/after comparisons here:

 - [A hand's on assessment of the new Canon EOS 40D][1] (page 6)
 - [Highlight Tone Priority - Image Salvation!][2]
 - [Highlight Tone Priority][3] 


  [1]: http://www.bobatkins.com/photography/digital/canon_eos_40D_review_6.html
  [2]: http://digitalprotalk.blogspot.com/2007/10/highlight-tone-priority-image-salvation.html
  [3]: http://www.digicamhelp.com/camera-logs/canon-xsi-450d/highlight-tone-priority/