Sounds obvious, but if you've got enough fuel and it's snowy, gather some to melt. Bear in mind though that you'll get vastly less water than you might expect, so be prepared to grab lots of it. Stay away from coloured snow as well, not just for the obvious reason but because very nasty bacteria can also cause coloured snow (pinkish as well as yellow.)
If there's no snow, have a look out for some common signs of water nearby:
- Increasingly wet or muddy/boggy ground
- Crevices in rocks (water naturally collects here)
- Converging animal tracks can often lead to a water source
- Insects - There tend to be more around close by to water
- Natural valleys, not just the obvious big ones but little ones as well. They tend to be where water collects.
- Dried up stream / river beds. Even if there's no water, follow them downhill and they may well merge with a running water source.
- Patches of green foliage, especially green leafy trees
If there really is no surface water, your best bet is probably to build a solar still if the conditions are right. You could also use green leaves and extract water from them via the same method.
Some sites recommend digging up muddy, boggy ground if available and letting the water drain out through a rudimentary filter made with a bottle / can filled with gravel, bark, sand etc. to filter the water. I wouldn't advice this unless you also have better purification mechanisms at your disposal such as chlorine tablets. Drinking water infected with nasty bacteria will make things a lot worse!