Iodine is ok, but my girls HATED it. I ended up using warm soapy water (Natural soap that is non-toxic. easy on the hands/udder yet disinfectant etc) and eventually will use essential oils too.
We clean the teats prior to milking with flannel baby wipes moistened with distilled water and drops of lavender oil in it. We don't treat the teats after we milk at all and haven't had any problems.
i pre wash the udder and teats, and afterwards i use warm water and dawn dish soap, just a drop and a splash of bleach and dip them, but my kids are not nursing them.