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 scene, 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..."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: