One of the keys to making good pressure in the sand is reducing tyre pressures. Compare two women of equal size walking across a patch of sand. The first is wearing dressy high-heels and the second is wearing a pair of trainingshoes. The first lady will struggle through the sand because her footprint is relatively small. The second will find walking much easier, because the same weight as the first lady is spread over a larger area and the downward pressure exerted on the sand is less.
This point might not seem relevant to driving in sand, but it is. By reducing the pressure in your tyres from the road, you can increase the footprint of your tyres and thus improve your vehicle's floatation.