You can start by safety and security (smoke/fire/flood - cameras, door lock) and go further into comfort (lights, switch, vaccum robot).
The most precious advice I could give is to write down what you need by priority. What are the main repetitive tasks you do when you come or leave home ? What should your system do if a fire event is triggered ? Try to prioritize your routines. You can start by safety and security (smoke/fire/flood - cameras, door lock) and go further into comfort (lights, switch, vaccum robot).