Summarize the following:
It’s perfectly fine to approach the celebrity and ask for selfies or autographs during fan events, such as meet and greets or signings. These events are designed specifically for fans to meet and interact with celebrities in a more casual setting. If you are able, it’s always a better idea to present a celebrity with fanart, a glimpse of your cosplay, or a notebook to sign at a public event, such as a convention or on the red carpet. Celebrities will typically be busy interacting with fans and the media already, making this the perfect chance to talk to them yourself! Just be sure to ask the event staff whether it’s okay to approach first. If you spot a celebrity while out running errands or enjoying a meal at a restaurant, you may not want to strike up conversation with them right away. Chances are the celebrity is also just going about their daily life and may not want to be disturbed. Most people are not willing to have a friendly chat while right in the middle of lunch. Let the celebrity enjoy their meal and, if you still want to approach them, only do so after they’ve finished eating. Whether it’s a face to face conversation or over the phone, celebrities (as well as any person) who are in mid-conversation should be left to finish that conversation before you attempt to start a new one. Walking up to talk while they are already occupied will leave a poor impression.

Summary:
Talk to the celebrity if you’re at a fan event. Approach a celebrity with a gift or request at fan or media events. Take caution with approaching a celebrity on the street. Avoid approaching celebrities during mealtimes. Don’t approach a celebrity who’s already talking to someone else.