I just got a “new” pair of running shoes that I just began to break in (it was given secondhand after it didn’t fit well w/ the previous owner). The size is a little bigger than my usual shoe size but given thats its a running shoe, its much narrower. I also bought some support soles on the salesperson’s suggestion – I don’t know if that might be an inadvertent cause of the blister. Right foot/shoe feels great and no problems – its the left foot that has a blister. Not too familiar w/ the differences of foot pronation/supination (my feet are medium-high-arched) so I don’t know if that’s a blister factor. I feel its too early to give up on these shoes though I will look around and consult on recommendations for other pairs. So while breaking it in and bearing out these shoes – any suggestions/experiences to help prevent/avoid/treat blisters and new running shoes?