In this high desert, avoiding the glare of human civilization is very easy. Just walk a few feet away from any road or camp, and you are in total darkness. Also, the low rainfall makes the skies clear most nights of the year.
Tip: To get the best view of the heavens, try to avoid the bright moon spoiling your view. Check the moon phase calendar here https://www.timeanddate.com/moon/usa/los-angeles
For first-time stargazers, I recommend visiting the "Sky is the Limit Observatory," located just before the north park entrance and Twentynine Palms.
A large group of like-minded people gathers to enjoy the heavenly displays every Saturday.
Many volunteers bring their large telescopes, allowing people to view the Planets and Star Clusters.
Tip: When walking in the dark, use flashlights with red filters. Regular flashlights create a lot of light pollution and spoil the view for everyone.
You don't need a telescope to enjoy the show. Use your naked eye or binoculars to see many stars, constellations, the Milky Way, and a few shooting stars.
If you happen to be camping at Joshua Tree, then all you must do is walk a few steps away from camper lights, where you will be plunged into total darkness.
Tip: It can get very cold at night in the high desert. Dress in layers and bring extra blankets.
As you drive around the park, you will notice those pullouts or small parking spots. Many of them are next to popular points of interest, like Cap Rock, Jumbo Rocks, and Skull Rock. Wherever you park, walk a few feet away from the vehicles to enjoy a great sky view.
How to watch the stars
During my first stargazing visit, I wasn't fully prepared. I was trying to view the sky while standing up. I enjoyed some of the views, but before long, my neck started to hurt from looking up. I also got very cold, even while wearing a jacket.
I advise bringing a sleeping bag or thick blankets to lie on the ground. Lie down and cover up to enjoy an amazing view above.