I used to wear the T90s with synthetic leather and I always used to get blisters on my feet. I recently made the switch to the Tiempo Legend IIIs with Kangaroo leather, hoping it will be softer for my feet. Is there anything else I can do though to prevent blisters??
You can tape your feet up with zinc oxide strapping tape, around the areas that tend to blister. I tend to get blisters on the undersides of my big toes, so I wrap a bit of tape around them and it really helps.
In the longer term, you can harden up the skin locally by applying surgical spirit to the area - it dries out the skin and it hardens over time (a period of weeks that is, not overnight) so tends to blister less.