Complete checklist for trip to australia?

i'll (hopefully) be planning a trip to sydney from louisiana sometime next year, and i need to know everything ill need. im going alone and will be 20 at the time ive done alot of research but want to be complete so i dont run into any complications. seeing as ive never left my country (usa) i am planning to spend 2-4 weeks it's more of a learning experience so include places to see if you can :D. i know i need a visa so you can leave that part out. the reason im only going to sydney is im traveling alone and cant drive a car legaly due to medication. ill also be bringing prescription meds so include info on that if you can. my main concern is my lack of expirence in airports and ill be going through the biggest airports in usa and oz so any tips there will be nice. dont lecture me on dont travel alone because the few poeple that can offord the trip/would want to come have ulseric colitis and cant even handle 10minutes on a plane,its a 22-26 hour flight. it's been my lifelong dream to go to australia and its getting closer :D i jus need help planning.