How do I stop foot odor? What can you recommend for especially strong foot odor?

Antiperspirant. The odor is generally caused by excessive bacteria due to either over active or an increased number of sweat glands. You can try a product such as certain dry. If that doesn't work see a podiatrist and get a prescription for a stronger topical medication.
See below. There is a product called bromi lotion. It works well.
Keep dry. Foot odor develops from bacteria and/or fungus on the skin that worsens with moisture and warmth. You might try changing socks frequently and using cotton socks to absorb and use a good absorbent powder such as zeosorb-af which also has an anti-fungal medication in it. If these do not work, then you should see a podiatrist or dermatologist who can offer other prescription items to help.
Foot odor. Try those suggestions - all work but not always. That's the difficulty. Adding a product you spray in your shoes will help ( see your podiatrist ) and : hygiene hygiene hygiene.