I have also been lucky enough to visit Death Valley on two occasions and getting good shots of the dunes can take some planning ...
- Best time is sunrise as the low temperature helps to reduce heat haze
that can rob your image of detail.
- Also sunrise is good due to the angle of the light, with it being low
in the sky you get lots of shadows which create contrast enabling you to photograph the detail in the dunes.
- Try to shoot the dunes at 90 degrees to the rising sun so that you
get maximum effect of the shadows.
- Yet another reason for sunrise is the golden light on the dunes turns
them to a beautiful golden colour.
- You can use ridges of the dunes to lead the viewer in to your image,
or get closeups of the abstract patterns of the sand on the dunes.
- Try to not include too much of the surrounding mountains or the
viewer's eye may loose focus on the sand dunes in the foreground.
Get to the dunes at least an hour before sunrise and park on the edge of the road about 1km west of the car park, this enables you to hike in to the west end of the dunes. I went in winter when the sun was rising to the south east so we we able to get to the far side of the dunes and get that angle to see the shadows & contrast.
Ensure you have a headlamp as it is very dark indeed once you leave the car. There is some risk as the desert wildlife are certainly about at that time of the day, but if you walk heavy the vibrations help to scatter them.
Walk up on to the top of the dunes at the edge of the collection of dunes, ensuring you do NOT walk in front of where you want to shoot. There are often strong winds over night in Death Valley that help to erase footsteps from the previous day (I was unlucky to get a morning with no winds the previous night so had to try and find "man free" views).
Don't forget to shoot from very low down as well as from eye-level standing as both have a different view of the same stretch of wind patterned sand. Of course always shoot with a tripod, it can be more difficult than people realise to keep steady on the edge of a dune for example.
It can mean an extremely early start, a slightly scary hike in the dark for about 40 minutes, and hard work getting up some of the taller dunes, BUT the results can certainly be worthwhile ... http://www.thetrueshot.com/Death_Valley_National_Park.html#10