1) No really drink more water - Two days after the event and I'm STILL thirsty - I did NOT drink enough during the walk
2) NEVER leave a pit stop or grab n go with less than two full bottles of beverage - you never know what the terrain is going to be like and if you'll need it
3) Practice on hills and pathways - not just sidewalks and mall walking (or treadmills). Saturday a lot of the walking was on the edges of roads walking on asphalt and we faced some fairly major hills each day.
4) The SMART people brought knit hats and gloves so that they had them available on Saturday night when it was freezing - what I wouldn't have given for a ski cap
5) Bring knee braces - the ace bandages that the medical stations had weren't long enough to deal with knees well and really ace bandages don't do a good job for knees anyway
6) Take pictures everywhere - and put an extra set of batteries in your fanny pack even for opening ceremonies
7) When doing training walks make sure you practice with your water bottles full and carrying everything you think you're going to carry on the walk - my fanny pack weighed a lot more than I expected it to with full bottles
8) Don't forget to bring scissors capable of cutting moleskin
9) Reconsider the fanny pack - I liked mine up until this event but the catch kept releasing at inconvient times. Maybe a backpack would be better?
I'm sure I'll add to this list as I think of things