1. Accept all the help you can get. Hospital visits, taking care of pets, organzing and paying bills, laundry and getting food. It all becomes difficult and you need help. Accept it.
2. Have someone you trust to talk to. Again you can't take on someone else's life tasks without help yourself. I had my better half, use the support of your family. Talking about decisions before you make them helps clarify situations and information.
3. Take care of yourself too. You can't help others if you are sick too.
4. Understand that sick people can be difficult. They are in pain and have little patience. But it doesn't mean you have to take abuse. If they get mean and rude, sometimes just leaving and going to another room helps but sometimes you just have to tell them to treat you with the respect you deserve. Don't feel bad about it. It just a part of life.
5. Don't second guess yourself. Decisions will come at you that you've never experienced before. You'll be in situations that you've never had to deal with before. If you get through them then you've done good. Sometimes there is no right way, there are just more uncomfortable ways.
6. Let yourself and others feel sad. You don't always have to be the one who brings the cheer and cake. And you shouldn't demand everyone look happy all the time. It will be tough, but you will make it through.
7. Friends and relatives will be the same after this. The obnoxious Aunt will still be obnoxious. The kind and caring person will still be kind and caring. This experience maybe life changing for you. But others will float through it without any notion about the importance of it.
So, that's the things I wish I knew before my uncle went into a coma, came out, had open heart surgery then lost his kidney functions. A year of hell for him but he survived.