Stone steps work best as a single slab of stone, set so that the top surface is level in both directions. Stone steps last longer if they rest on top of the step beneath them, with a 3″ overhang. I set steps into a bed of crushed gravel, compacted.
Steps work best for pedestrians when the top surface is smooth, and when the height of each step is very similar.
For stone steps in the landscape, I advocate the use of handrails made from metal or wood.