1) Plan well in advance (like 3+ weeks). This post 'suggests' that this should be #1 for Emp 1.1. Last minute?
2) Do your passport homework - is a visa needed? (no, since you probably don't expect to stay over 90 days).
3) Are you stopping in a city before you take a second flight to Poland? (Likely). Then be ready for passing through customs/immigration and a possible 'electronics inspection' - not the same as here in the US. Could be fun!
4) Thought about the local currency and conversion? You should or you could be ripped off. I can send you an Excel sheet to use.
5) Be careful with your credit cards (bring just 2, max). Call those two and tell them where you're going (unless you used one of them to buy the airline tickets, etc).
There's more but you have no time...