use fingerless gloves (weighlifting or biking gloves) as they will protect the palms but still allow grip where needed...
a long sleeved underlayer with a rough old vest/short T over the top will keep you "warm" and prevent abrasion. same with shorts - lycra ones under, something lke football shorts over. and as NC says - no cotton - use tech kit.
fell style shoes with grip work best - I use Inov8s - and use knotted laces that don't pull through the lace eyelets to stop the shoes getting sucked off in the mud, and even then use a double knot when you lace up.
and if there are any sections where you are crawling on your knees - use some knee protection (an old pair of knee supports or similar) or they will skin and sting like hell after!