here's for when you throw the guide doll into lava
For one, GET ROCKET BOOTS. This way you won't fall so much.
Two, a good minishark with 1000ish bullets.
Three, get a small house with a bedroom right near the ash layer incase you get mauled anyway. And get a distinctive path back to the overworld.
Four, DO NOT FALL INTO LAVA. Get an obsidian skin potion if you can't at least manage that.
Five, wear sunglasses in the vanity slot for extra oomph.