The nice thing is you can pretty much follow the person in front of you. Schipol is very nicely laid out. Signs are in two languages, one of them is English - so it's easy to find your way.
Last year, there were significant issues with security lines at Schipol. Lines were crazy, the Pilots' Union even volunteered to help. Unless those have been cleared up, you won't want to wander outside security during your layover.
If you're not sure what you need to do, ask. The Dutch are great at languages. If you speak to them in English (German, French, etc.), they'll respond in perfect English (German, French, etc.). If I could speak Icelandic, I test them on it.
Likely the only place you won't follow the person in front of you is when there is a sign directing people to two lines - one for EU citizens and the other for non-EU.
CDG isn't as easy as Schipol, but it's the same idea. I've taken a few wrong turns in CDG but always ended up where I was going. Biggest thing I find different in France is using credit cards in machines. American cards regularly get rejected. My theory is they time out before getting approved. Try a second, or third, time. They seem to work eventually.
It doesn't sound like you are going anywhere other than Schengen countries, or for more than three months. Schengen is simply a multinational agreement that, for one, allows US citizens to visit without a visa for up to three months in a six-month period. U.S. Citizens who want to travel for longer than three months need to plan some of their time in non-Schengen countries (U.K. for example).