I did an adventure race, and decided it was too much for me - i don't like the HAVING to train for every single thing. I would start hate being outside.
Anyway, that being said - if you have done orienteering before - maps are sometimes not great quality - keep that in mind. Also, when "aiming" your compass on the map, aim for the middle of something rather than the tip - for example like a lake. this wasn't obvious to me, but when there are many lakes in an area, its hard to know which is which once you start bush whacking. We walked right by our target lake and found another one, had no idea and ended up very very lost. So by aiming for the middle then walking around it, you will end up where you need to be.
get good socks.
those are my only bits of wisdom
have fuN!!
Han