Tried and true, time tested system....
before going to bed or if able to during day, especially before a tickle session:
1) lotion feet with natural ingredient lotion (the shorter the ingredient list, the better!) or raw shea butter (I can tell you where to get that)
2) put on pair of light cotton socks
3) put a plastic shopping bag over each socked foot
4) put on a pair of heavy wool/cotton socks over the bags (you will sound crunchy walking around so be prepared to field questions and weird looks from family or friends or do it just before bed)
- let feet "baste" overnight or for 4 hours or more
- your feet will be sweating in the socks and bags and will come out rather
aromatic (some of us actually LIKE that!

)
Your feet will come out very soft and moist and to keep them that way before a session, wear heavy sneakers with no socks or HEAVY/WARM socks or other enclosed shoes to keep in the moisture and warmth. You will LOVE how sensitive and soft they are once you unwrap them and will want them tickled right then and there...you may want to try to do it yourself...I know I have!

.....but relotion as needed after a treatment like this and repeat the second night if you are really hard-core for being soft-footed!
I am not a fan of scrapey things and files and stuff, though my partner uses them from time to time. There is no substitute for a good long soak in Footherapy and warm/hot water....except my little aforementioned recipe for the softest feet you'll ever love....or get tickled!
Um....and send me pics of your feet after you unwrap them so...um....well....I know that you've....um....done it right....yeah, that's it...!
Happy Feet!