If this is your first time going here is some advice.
book your FP for your 3 most do rides in the park ( some parks have tierd FP)
get to the park before they open ( like an hour) sometimes they let you in early.
Use EMH and take a break during the heat of the day if need be. ( early morning and late evenings tend to be less crowded
You will not see and do every thing so do not try ( unless you are there for a month).
It gets hot and humid at Disney in September ( and really most of the year) so drink a lot of water, if you think you have enough drink some more