The radox bath salts are great as a soak, especially in a foot spa.
I tend to stick some natural seasalts in with it.
I always find going for a luxury pedicure helps too, you can get different treatments like for heavy achy feet and the warm wax is fantastic.
Keeping them cool and raised helps as well and I find properly comfortable, fitting and supportive footwear is a must especially if you spend a lot of time on your feet. Ranges like M&S Footglove and some of the Clarkes ones are great.