Hey Ant,
We do lots of beach driving over here, in fact that's the only 4 wheelin' I do.
I run tyre pressures between 18 and 15psi. This should be soft enough to keep the beads on and roll through most soft sand, also good pressure for general 4WDing as it does less damage to tracks.
If for some reason, you do get bogged, don't sit there spinning the tyres. Spinning tyres are bogging you worse. Instead, drop your tyres to 12 psi and try reverse SLOWLY then 1st SLOWLY back and forth and "rock" the vehicle forward and backward. The for and aft rolling presses the sand down and compacts it. Go a little further each way as you go but don't spin the wheels. Once you have a compacted patch of about 3 or 4 feet long, use the run up, accelerate smoothly and keep going using the momentum the other guys are talking about and you should drive out.
With tyres down as low as 12 psi, no hard cornering or high speeds, stay below 40kph and pump them up when you can as you can overheat the sidewalls causing tyre failure not to mention rolling them off the bead.
Don't drive too fast and avoid harsh turns as many a 4WD has ended up on it's lid by fanging along and "snaking".
Make sure you are in a gear with plenty of torque so if you hit a soft spot you wont have to snatch a lower gear. As soon as the clutch goes in, the car stops.
When driving down dunes, don't use the brakes but keep the tyres turning in a low gear and accelerate if need be. No fun when the rear end overtakes the front end down a hill
If you are driving up a hill and you can't get up, don't turn around to come back down, reverse down again and try again. It sounds obvious, but I see numnuts do this every weekend at Lano and they usually end up in a roll over.
Make sure you have a pressure gauge and a set of Straun tyre deflators (worth their weight in gold), a snatch strap, quality bow shackles, and a compressor (even a relative cheapie) will do the job. I started with a $79 Auto shop cheapie and it did the job for a few years (however slow and painful). Now have a Bush Ranger which is awesome!
Have fun! Sand driving can be challenging and is easier if you follow someone elses previously compacted tracks.
Get into it!
DJ