from your cellular / mobile phone:

This will be the easiest way, but probably also the most expensive.
 
Ask your contract provider whether you will be able to use your cellular in Germany (keyword roaming) and if so, about the costs.
To reduce the costs, you may wish to try one or both of these options:
 
Option #1:
Use an international connection service, for example
• JAJAH direct or RebTel
 
Option #2:
In case your mobile phone is not SIM-locked consider to buy a German prepaid SIM card after your arrival in Germany. We currently suggest
• FONIC
due to their low rates for calls to many international destinations.

from a German fixed line phone:

In most cases this will be by far the cheapest way.
 
If you have access to a German fixed line phone, operated by Deutsche Telekom, you will be able to use a dial around service (as a U.S. citizen you may probably know the 10-10 codes - in Germany we call it call-by-call).
 
Enjoy extremely low rates - for the costs for international calls using call-by-call from Germany see our
• Phone Rate Comparison

from a German public payphone:

Still an easy way, but international calls are quite expensive unless you use a trick.
 
For how to use a German payphone, including costs and saving possibilities, see
• The Foxy Phone Page

internet access:

Many internet cafés offer their service. Rates should be less than 2 EURO per hour. Look up
• German Internet cafés...
 
If you own a notebook equipped with WLAN, visit a hotspot. Look up
• hotspots in Germany...
 
If you own a notebook equipped with a dial-up adapter, simply use FREE dial-up which is instantly available - without need for a sign-up. Just the normal land line phone rate for a call to a German fixed line phone number applies. See
• The Foxy Phone Page
for access numbers, username and password.