There 2 easy ways to prevent poisonous moonshine. The first is throw out the first 5% of distillate. It tastes terrible and contains the majority of the methanol. The second is mix all of the distillate together at the end of the run. This distributes everything evenly, and prevents some bottles from being 85% abv(170 proof) while other bottles are 30% abv(60 proof).

In related news, if you're drinking dodgy booze, make sure to occasionally do a shot of non-dodgy booze. The cure for methanol poisoning is ethanol.