How can I be cool when meeting one of my favorite singers?

Low cut dress?

@XOIIO Haha! Added to the list.

However, I often freak out when meeting celebrities I really like.

You meet a lot of celebrities?

Be polite, be friendly, smile, and ask them something about themselves that shows an interest in them as a person, not something intrusive onto their private business. And be realistic that you are not going to become friends, this is their work, how they earn their living. Thank them for the happiness you receive when you see them play or hear their music.

Depends. Who are you meet and greeting?

What I would say would be far different if it were Yo Yo Ma, versus, for example Dr. Dre. Can you help narrow down the possibilities?

Treat them as regular people, just with a different job. Most people in that line of work love a real connection to another real person.

Why try to “be cool”? Just be yourself and tell them exactly that you said above: “I am in love with your music so much, and meeting you is a dream come true to me.”

Take a deep breath and pretend he’s your neighbor. They get chased by the press and stalkers, they just usually want to be treated like normal people with talent. :)

You can do it!

Be yourself. That will make the biggest impression.

Tell him his music sucks.
Then faint.

Don’t force yourself to be cool. Just be yourself.