Put the camera away unless every identifiable person has clearly agreed to the specific photograph.
Good consent is specific
Permission to take one private photograph is not permission to publish it, tag it, keep it indefinitely or use it elsewhere. Explain what you want to capture and how it will be used.
Make “no” easy
Ask without pressure and accept refusal immediately. Check the background for people who have not agreed. At venues and events, follow the organiser’s rules even if an individual is willing.
When in doubt, enjoy the moment without recording it.