My Skull Cavern Kit for mostly guaranteed butt-saving:
Slime Charmer Ring to ignore Slimes forever, very important for staying focused
Iridium Ring for multi use esp. magnetism for quicker pickups
Space Boots or better
Galaxy Sword or better
150+ Stairs to get down to Level ~100 to start Bombing
50+ Bombs (aww I gave it away above)
40+

Cheese or your favorite Food
2-3 Spicy Eel for Speed and Luck
10+ Ginger Ale for more Luck
General strategies after Level ~100:
* Skip "good" looking loot levels before 100 unless they are both safe and very tasty-looking. There will be better ones later.
* Eat Cheese all the time. You get boo-boo, you eat teh Chez. No arguing! Chez is cheap, you are not.
* Skip infested Levels (with Stairs) or ones with too many monsters, especially Flying Serpent Knee Nibblers. I don't care what you saw on those Levels, there will be moar. SKIP!
* If you find a chill level, Bomb it anyway for a break. You deserve Booms, too.
* Remember to watch your Luck from Eel and Ale, you'll use most/all of both during one day's run. These really help for Treasure Rooms which are like free Levels plus
L
T!
PS: If you're a little later in-game, try replacing Spicy Eel + Ginger Ale with Lucky Lunch + Espresso (or Coffee) as Lucky Lunch gets you a LOT of Treasure Rooms.