Hmmm. Looks like my last post got truncated somehow. I think it should have had six tips. The best ones got dropped. I can only remember three of them now.
3. Puddles of water are often the best line through thick mud. The water dissolves the mud, so it gets pushed aside easier letting your tire get to solid ground. The mud that isn't under water is more likely to be peanut butter.
4. Watch what happens to the mud where the person in front of you rides through. If the mud quickly flows back to fill the track behind the tire, that's the line you want. If it leaves a well-defined track, stay away. More slosh = less resistance.
5. When you get home, grab the garden hose and spray your muddy clothes out from the inside. Too much pressure probably isn't good for the life of the fabric, but you'll be surprised how much of the mud this technique eliminates. Doing this got my jersey cleaner than either soaking or washing. I've been hand-scrubbing the mud all season, and didn't stumble across this until the last race of the year.