Heard on the radio the other day (from some potato expert - radio 4 not soe obscure gardening one!!) that keeping potatoes in the plastic bag they come in stops oxygen getting to them & starts the rotting process. Ideally they are stored in something breathable but just tearing a small hole in the plastic straightaway also has a beneficial effect. Tried this over the last few days & potatoes are now much better.
PS if you have any other storage techniques I am all ears