Skull Cavern is best approached as a planned expedition. Unlike a casual Mines run, deep progress depends on preparation, time management and avoiding unnecessary delays.
Prepare before leaving the farm
- Bring strong healing food.
- Bring bombs or another fast way to clear clustered rocks.
- Leave enough inventory space for valuable ore and drops.
- Use a weapon and pickaxe appropriate for the stage of your save.
Descent is the main objective
If the goal is reaching deeper floors, do not stop for every ore node or enemy. Prioritize ladders, shafts and fast movement when the side reward is not worth the time.
Use the day efficiently
Start as early as practical and reduce unnecessary travel. The more time spent outside the cavern, the less value you get from consumables prepared for the run.
Healing discipline
Do not wait until health is critically low. A safe heal is cheaper than losing the run because one enemy connects during a dangerous floor.
Know the purpose of the run
A resource-focused run and a depth-focused run are not the same. Decide whether you want ore, treasure, monster drops or floor progress before entering.
Source: Stardew Valley Wiki — Skull Cavern.