Wearing armour and using TNT are allowed, so take advantage of that.
Potions are always good, but even moreso here. The Strength potion will let you do 2 damage instead of 1, and Swiftness will let you run away faster.
Rolling across ice is fast, and a good way to run from enemies (and get the Smooth Operator achievement, if you don't own it). Try to only fight 1 - 2 enemies at once, and only fight what you absolutely have to. (i.e. enemies in your direct path, and the arena ones)
Ignore basically everything that isn't the main objective (pots and chests can be claimed if you want the loot, just remember not to equip any weapons)
I'd advise Renegade Armour since it gives 35% Damage Reduction.
Enemies scale based on your power, so do the lowest difficulty and use Creepers to kill them (the creepers will only do around 25 damage to you, and with a decent armour set you'd be up to ~120 or more health)
Other than that, follow Im King Logan's guide and you should be ok.