The short answer
Choose one part of the city, one main experience and a flexible second stop. Build in time to walk, eat and rest.
Group places by location
Mark your hotel and the places you hope to visit on a map. Pick a nearby cluster rather than criss-crossing the city for every stop.
Keep one flexible choice
A garden, museum or neighborhood walk can take longer than you expect. Make the second activity optional so the day still works if you slow down.
Adapt for the people travelling
Ask about walking comfort, dietary needs and preferred break times. Accessibility, language support and admission arrangements should be checked with each venue.