Ride loose on the bike, let it work for you. Fight and force the bike and you will end up arsesliding down the track. You may need to be somewhat aggressive in weighting the front end however.
Don't be afraid to back it into corners, a sliding rear end often prevents a washed out front.
Use terrain contours to control momentum, brake early and with less force.
Look for 'loamy' lines, slick or sloppy ones won't hook you up. Don't be a sheep. Puddles look bad but are often very firm underneath. Sparse grassed surfaces are a great secret weapon.
Hit rocks, roots and built terrain features square on to reduce the chances of washing out.
Otherwise, go with the flow.
[rant]
As for racing, in their infinite wisdom the ruling bodies down here in Australia shifted the bulk of state and national series to a summer format in the closing days of the 1990s, so that a handful of pros - who these days probably won't actually race those series - could attend, as the world cup/championships tends to be in the northern spring/summer/autumn, or our autumn/winter/spring.
Thus these days, its rare to have a race above club level in what I would consider 'mud' at all, which is a crying shame.
Then again, a few muddy races and most of the popular virtual pivot bikes with their overcomplicated hardware and miniscule pivots would damn near disintegrate anyway.
[/rant]
