Smart home systems range from DIY plug-and-play (Google Home, Amazon Echo) that don’t need any pre-wiring to full custom systems (Control4, Crestron, Savant) that require careful pre-wire planning. For a Lutron Homeworks or RadioRA system, you’re typically running a Lutron-specified wire type to each switch and keypad location that homerun back to the Homeworks main controller.
The Lutron pre-wire guide is actually very good - download it and follow it. The cost of doing it right during pre-wire versus adding wire after sheetrock is enormous.
For mid-range: Lutron Caseta (wireless) and similar systems don’t need pre-wire, but you do need neutral wires at every switch location. A lot of old homes have switch loops (no neutral at the switch) - pre-wiring these with a neutral is a huge value-add for smart switch compatibility. Run a 3-wire plus ground from every switch to the closest junction point where a neutral is available. Future you will thank current you.