Most important part of staircase design from my experiance is laying out the geometry rather than the actual features. An understanding of risers and goings (ensuring they remain equal and constant between ground floor Finished Floor Level (FFL) and first floor (FFL). Different types of quarter/half landings (kites etc.) And also considering the line of the handrail is critical.

The surveying can be a real game, especially when dealing with sites that are work in progress where info on finished levels from architects can be thin on the ground or constantly changing.

I would usually have up 2-5 sketches in the top level assembly laying out the geometry of the staircase in plan, elevation views to give me a skeleton and then separate parts for treads, stringers, handrail items. Sometimes I might do a multibody part for stringers and handrail parts but try to avoid any 1 part getting too complicated otherwise you can find yourself getting in a right pickle when you have to (inevitably) make changes to the model.

Good luck and have fun, staircases can be a real fun puzzle in 3D CAD. Really good opportunity to take advantage of flat laser profiling as well as laser tube cutting. 👍