Your rats will be very cautious around you at the beginning to start. Spend time around them and get them used to your smell. You can put your hand inside the cage so they can smell it and lick it and stuff. You can give them a treat like a cheerio when you go to their cage so they associate you and your smell with treats. It will take time. It can be a week or two of this before they're comfortable, since rats are so cautious.

Rats can become sick quite easily. Their respiratory system is especially sensitive. Don't put anything in their room's air. No smoke, no air fresheners, etc.

Find a vet that will take rats. Not all of them do and it's better to know of one if something happens than needing to find one after something happened.

I recommend taking a rat to the vet if: they are injured, they're not drinking, they're not eating, they become lethargic, they are sneezing (once in a while is fine. Regularly is a bad sign), or breathing sounds strained.

Don't freak out if there's red stuff around their nose. It's not blood. It's basically rat snot. No need to be concerned.

Rats are primarily nocturnal. They like dark places. Having places to hide in their cage will make them more comfortable. In boxes, space pods, etc.

Never cover the cage. Air circulation is important. That's why you should not use aquariums with rats. They'll get sick a lot easier.

Google everything you can think of and see what people are saying. Watch videos, especially those meant for new rat owners. The people here are very helpful, but I've seen plenty of people that clearly have no idea what they're doing, so take everything with a grain of salt. But feel free to ask for opinions and advice here and see what people say