What to expect at a funeral and viewing?

I am 20 years old, and I've been quite fortunate to not have had to go to a funeral yet in my life. Last Friday my Aunt that I was very close with killed herself, and the viewing is tomorrow. What should I expect? It is open casket and I am afraid to see, but I think I will anyway. What should I wear? And any other tips please be sure to tell me. Thank you