Without repeating what has already been said, my fool proof way is to use the Phoenix Blaster with Meteorite Shots. It's an absolute life saver as you can take out the Wall of Flesh without any buffs at all, in as little as a 500 block runway (though give yourself some breathing space) and only lose around 5 or 6 hearts (with Molten Armour).
You can craft the gunphoenix blaster with a regular handgun (commonly foundfound in locked gold chests in the dungeon) and 20 Hellstone bars. Then combine regular ammo with Meteorite bars to create Meteorite Shots.
As far as strategy goes, use a big blade (Night's Edge makes it easy) to deal with all of The Hungry first. Then lay into the Wall's eye with the blaster - on average I expend around 250 shots though they are really easy to stock up on so I wouldn't worry about being trigger happy.