For me its mainly the arm pits, thighs, instep, soles, i can,t say my toes are ticklish to a large degree.
Regarding tickling a lee it will be a general tickle all over until i find the area that works best both for me and the lee.
I may enjoy tickling feet but its no use if the lee likes to have their pits tickled.
Once i find their weak spot i won't go directly for it but go everywhere else, then work toward the "tickle hot spot" and take it from there along with the appropriate tease ie baby talk, blindfold, gag, or whatever they like most.