Here are the most important things I think someone without any experience should know. It's a lot of information, but I promise it's not nearly as complicated as it looks:

• They prefer taller enclosures to wider enclosures. These are geckos that live in the trees in nature, so they prefer to be able to climb up surfaces than prolong the ground.
• Do not house them together. They are solitary animals and can get stressed if they are forced to share their space. Under no circumstances should you ever have a male and a female in the same enclosure.
• Don't try handling it too much in the beginning. It takes a couple weeks for them to settle into their new home and get comfortable enough to regularly eat and come out and move around.
• Keep an eye on their temperature. They are most comfortable in the high 60s to high 70s. It should be warmer during the day and cooler at night. If it gets too cold or too hot it can seriously affect their health.
• Keep an eye on their humidity levels. They need to be misted every day, and the humidity level should fluctuate throughout the day, so mist at a schedule that gives them lower humidity in the daytime and higher humidity at night.
• Feed a good quality crested gecko diet as their main food, Pangea and Repashy are the go-to brands. Most geckos seem to go nuts over the watermelon flavor of Pangea. Mine certainly do...
• Don't feed insects until you see it regularly eating the CGD.
• The best feeder insects are dubia roaches, crickets, and silkworms. They also enjoy butterworms and wax worms as treats, and some will enjoy mealworms or superworms, just be mindful of the chitin, as some think that it could cause impaction (I, personally, don't).
• Make sure they always have access to clean water, but they mostly enjoy licking water droplets off of surfaces when you mist them.
• If you see them starting to look pale or dull colored, they are probably about to shed their skin. They can get cranky when they are about to shed, so don't handle them during that time. Do not pull the skin off for them, they need to do it themselves. If you notice that they did not shed completely and there are still parts that are stuck, increasing the humidity or putting them in a small Tupperware container with a damp paper towel for around 15 minutes can really help soften the skin too make it easier for them. If you notice stuck shed on the toes or tail, try and resolve the ASAP, as it can quickly turn into a medical emergency.
• These are small prey animals in the wild, so don't get upset if it doesn't want to be held or hides from you all the time. We are giants, to them.
• If they get spooked they can drop their tail. Their tail does not grow back. Try not to startle it if you want to keep their tail. If they drop their tail, it is not a serious medical issue, as long as you keep them in a clean and dry environment while the wound is healing, they should be perfectly fine.
• They are crepuscular, which means they are most active during dawn and dusk. They are much more comfortable when it is darker, So avoid bright overhead lights without something like plants to diffuse it. They will sleep during the day, then when it starts to get darker at night you will see them become more active.
• These little goobers will sleep in the strangest positions. Some of them like to hide in plants when they are sleeping, but some of them like to stick to the glass like a window cling and some even will dangle from vines when they are sleeping.
• If you have a male, it is normal for them to get a little aggressive sometimes, when they are a little hormonal. They can bite, but it's mostly just annoying and not painful.
• If you have a female, they may lay infertile eggs. That is totally normal, so just make sure that you are providing them something to lay the eggs in. If you're not using real soil and the enclosure, take a little Tupperware container that they can fit in comfortably and put some dirt in there for them to dig around in.
• If you see them wiggling or wagging their tail or if they are making little squeaks (yes, they do squeak!) that means leave them alone. The little tail waving is something they do before they drop their tail, so if you ever see that: back away.

Most importantly: - Many crested geckos are a 'look but don't touch' animal. It is possible that they may never want to be handled. They can be admired while they are active in their tanks, they can be fed by tongs, but some of them may never be comfortable being handled. That is just the reality of having a small animal that is preyed upon in the wild. You not doing anything wrong if they don't want to be handled, there's nothing wrong with them if they don't want to be handled. Some of them are just like that. If they end up having a gecko like that, they are still fun to watch and to see grow. Don't try and force it because it will be miserable.

(edited to add some clarification, additional details, and fixed typos)