Read the stage before you enter
Each stage shows its enemy theme and its length before you start. The early ones are short and forgiving. The later ones add hazards that punish a thin build.
A stage you cannot finish teaches less than one you clear twice. Clear, then push outward.
What changes between stages
The enemy mix shifts what your weapons need to cover. A stage full of fast runners wants area. A stage of tanky enemies wants sustained damage.
Boss timing also moves. Some stages end sooner, which changes how much you need to scale.
Farm the first one first
Your first stage is the safest place to build gold and unlocks. Run it until the menu options open up, then move on.
The secret characters and coffins page notes that some stages hide what others do not.
Next: Boss strategies that work.