Have a plan. Try to stick with it, but go with the flow.
Know which park opens early or stays open late.
Use Fastpass.
Plan some down time.
I think being from another country you will need plug adapters (I think)
WDW resorts have washers and dryers. Try to do laundry during down times (Kids are in the pool and dh can watch them or first thing in the morning before the parks)
Break your shoes in before you go. Buy Moleskin.
Plan for the unexpected.
Get a refillable mug.
Learn the layout of your resort before you go.
These boards are a GREAT place for information. If you ask a question, someone will help you.