What are some things I should do to get ready for my first trip to central europe?

I would agree with much of the above, except to say that more people will speak English in Poland than in Slovakia. The languages are not the same, but are similar, so go ahead and learn important things in both languages. You'll go far in keeping the locals happy. And when they are happy, your interaction with them will be a happy one.

Make 2 photo copies of your passport and leave one copy home with someone reliable, and take one copy with you in a separate piece of luggage. Never carry it and your passport together.

One thing to remember in these countries is they are generally much quieter than America. MUCH quieter. In Slovakia, when you're on a public bus or train, you don't hear anyone talking. Maybe a low murmur of combined whispers, but that's about it. (From what I remember, Poland is the same way.) VERY opposite a typical American college group. People in this area equate loudness with drunkenness. Be sensitive and be quiet. Close your mouth and open your eyes and you'll have a much better experience as you won't be bringing America with you, but you'll absorb the places you're in... that's the reason you're going after all, isn't it?

Poland & Slovakia are not so much "eastern Europe" anymore. Enjoy yourself and have fun. Stay open to new ideas and new experiences.

Pack a lot of cash...i know this because I'm from Krakow and there you will want to buy good things like memories and there are nice chicks in Poland so say "Ja kocham Polske" and they might like you and make sure you exchange some American money for Polish zloty and try not to get arrested by the cops there...They are strict and they never joke around...If you take your American driver's licence then you can drive a car there for 30 days or if you have a international licence then you can drive for 60 days i think...And go have fun because Poland especially Krakow is the best...