Ive done a few Nijmegens and ran around hills in North Wales and Brecon, I'll give you my advice if you want it. Foot care is a dark art and has a different solution for everyone.
1. Nails: Keep them short, trim them regularly, use emeryboard/nailfile to keep nail edges smooth and snag free. (Sounds gay but stops toenails from rubbing on neighbouring toes and causing blisters)
2. Feet: Don't use urine on them (it will break the skin down), keep them moisturised if dry (E45 creme) and avoid cracked heels.
3. Socks: Massive difference of opinion here. I personally go for a cotton inner (thin) with a woolen outer (thick).
4. Dressings: Only apply to feet if you have a blister, don't strap feet as a preventative measure, it just cases friction, rubbing and will cause a blister. Catch 22.
5. Boots: Well fitting, worn in, waterproof, breathable, lightweight.
Good luck. Sore feet suck but sometimes you just have to suck it up and crack on. No one set advice is the definitive set of advice, from my experience just try a selection of tips, and try it yourself.
Yeah im rezzing a dead thread here but it caught my eye.