>what do they need to know/have to get their first successful use?

Ah, the age old question: how long is a piece of string?

The question you pose is best answered by more questions.

What do you want to do? Wide angle full sky type imagery (think full night sky with Milky Way tracing across the image)? Planetary images (I'd suggest not starting here)? Deep Sky Objects (nebulae, galaxies, star clusters, etc)? Each one of those requires different equipment.

Wide angle full sky stuff can be done with a tripod and a camera. After that, you will need gear that can start "tracking" the sky. Basically, a method to counter act the rotation of the earth. Many ways of achieving this for just mounting a camera to a tripod.

Say you want to go further, you'll start looking at telescopes. Which telescope depends on what you want to image. Now that you have a telescope, you'll need a mount. I'd highly suggest an equitorial mount.

Now you need a camera to mount to that scope. Again many options exist. You can get a mount that allows you to hold your mobile phone next to an eyepiece. Works great for planetary/moon shots as they are bright enough a long exposure is not necessary. If you want to use a DSLR you already have, you'll need some method of connecting it to the telescope usually with a t-adapter. It connects to your camera like a lens, then you slide it in place of the eyepiece. Now your telescope is your lens.

All of sudden, you start realizing that your mount and motors just are not accurate enough, so now you want to start doing guided imaging. Oh boy, now you need a smaller telescope for your telescope. That new scope will need it's own camera. Depending on where you're going, you can get a new camera that is also a guider or one that needs to be plugged into a laptop for control. Oh, so you'll need a laptop you don't mind being out all night and susceptible to dew etc.

Once you have your guide scope being guided by something, you'll get to start learning about stacking. Instead of taking a single exposure for 60 minutes, you can take 60 one minute exposures. Then there's more software that allows you to take your stacks and align/process them.

Okay, so now you have all of this equipment to take great images. You'll need a way to transport it. Great, put it in the SUV. Now, your schedule will need to align. Certain nights are better for imaging than others. Full moons are the wrong time for viewing anything but the moon. Great, shift your schedule for new moons. Perfect there's one coming up, but the Mrs has already made dinner plans with someone you may or may not care about, but you won't be using your gear that night. A free weekend lines up with a new moon and you've received permission from the Mrs to go play. Oops, its cloudy AF, and you're left dreaming once again about the imagary you'll someday be able to take.

I love my hobby enough to be that cynical.

Edit: I always focus on the tech gear, but there's some other basics need too. As many red filters as you can find. Flashlights with red filters are a must. Lots of headlamps now come with red LEDs as an option. Red filter your laptop screen whether with actual filter or an app that changes the screen tone. Warm clothes. Because of heat distortion in the atmosphere, lots of good viewing during winter. Winter gets cold, and it's never as cold as when you're trying to achieve focus with 10 little blocks of ice at the end of your hands. Also, be aware of the car you are driving. Can you turn the headlights off when the car is on? You'll be tempted to sit in the car with the heater running, but some cars always have running lights that you cannot turn off. Also, check you car's interior lights. If you need to keep running back to the car, that interior light coming on/off will become annoying. If not annoying to you, anyone else imaging that night will start to get peeved at you.

The other thing I'd suggest is friends to take with you. Sharing the experience is so much more rewarding. If you have no friends, at least not interested in staying up all night in remote locations, then find star parties. Get involved with local groups. It's easy to get defeated, but going to meetings and chatting with others helps keep you excited about it.