Ok I bough new shoes yesterday and I wore them in at home. Wrong! I wore them out because well they're new and I love them. So I came home with a whopping fluid filled blister on each reddened heel. After a bit of google's-your-friend, I decided to pop them last night, so swabbed down with disinfectant, disinfected some pointy nail scissors, jabbed a hole at the bottom and pushed the fluid out (are you all enjoying the detail over your sammies?), disinfected again, covered with plasters in a cross. Left overnight. Epsom salt bath this morning and all clear to run, good as gold and completely painless.
Of course you can just leave blisters to heal but not if you're a stubborn runner. Important to keep them clean, obviously disinfect your scissors or needle if you're popping them and don't tear the covering skin off. Best to leave it.