What is the first thing you do after a foot wound? For chronic wounds, what are the appropriate treatments?

What kinds of wounds? split skin or bed sore type or ???
If it is a cut i suggest cleaning with alcohol for dirt, then peroxide for disinfect, (it will stop foaming when the disinfecting is done).
To keep pain/swelling down, alternate hot and cold in running water quick-baths, then always a clean bandage.
For swelling elevate feet much higher than hips.

definitely see a medical professional if you're diabetic and incur anything more than a paper cut... especially if you can't see it properly!