Prevent and treat blisters

[Deleted User]

Did a long race at the weekend and had a blister at about mile 40. Popped and treated with compeed and carried on. Very wet weather and had to stop and treat several more (about 10 major ones) before finished which was sore and time-consuming. Also found blisters under the compeed and very difficult to remove the compeed to treat.

Running with normal road shoes - 3 different pairs with my standard socks. All shoes had 100-200 miles on the clock so adequately worn in. However rained throughout so regardless of shoes changes had wet feet.

Anything better than compeed for carrying on and any tips to reduce the likelihood in the first place?

Advice appreciated.