First, what NOT to do. Do not just tell your wife you have a foot fetish! Don't get me wrong- I do think people should be open and honest about their sexuality however just as with D/s, many people have preconceived notions of certain things. Instead, introduce it to her slowly.
Begin by conquering any objections she may have. Some women are self-conscious of their feet. Face it- women's feet take a lot of abuse! From high-heeled shoes to open-toed sandals - women do not buy shoes with comfort in mind. A good beginning would be to send her to the spa for a manicure and pedicure. She (and her feet) will be pampered.
Now the fun begins! Of course you will want to check out her new manicure and pedicure. Compliment both her hands and her feet. Then, when curled up on the sofa, rub her feet gently. This really should not be a sexual activity but more a sensual, loving time. She should not feel that you are aroused by this but rather that you are contributing to her pleasure. I enjoy having my feet massaged with lotion. The Body Shop carries some great peppermint lotion just for feet. Begin making this part of your routine.
Now that she is becoming more comfortable with you touching her feet, introduce it in a more intimate setting. Kiss your wife from head to toe. Start by giving her kisses on her forehead then work your way down her face, slowly down her body and down her legs. This should be an act of love and appreciation. Although the end result will likely be sexual, this is more an act of devotion and sensuality. Most women will slowly become aroused in the process and by the time you reach her feet she will likely be more willing to accept your kisses there. But no sucking her toes... yet.
Gradually make her feet more a part of your day to day life with her as well as your intimate time. Make the effort to learn about how to give a great foot massage. Send her for pedicures regularly (or, even better, learn to do them yourself).
Now relax, continue to worship your wife's feet and let her take the reigns. She may enjoy your foot fetish just as much as you do!
From my experience, it took me a while to eroticize my feet. I have always appreciated pedicures and foot massages but one night, when j was rubbing my feet, it just felt so erotic. Partly it was because he hit this certain spot on the sole of my foot that feel so incredibly arousing! Now it is great foreplay. Now I enjoy having my feet kissed, licked, sucked. I use them to tease j, to play with his cock under the table in restaurants. In fact, my feet are one of the sexiest parts of my body. (In fact, it is fitting that as I have been writing this post j has been giving me a pedicure).
Best of luck as you explore this with your wife!
