While Americans are usually very understanding and welcoming towards foreign visitors, Via Her has listed a few tips and suggestions to help you avoid any cultural faux pas.
American Core... 
U.S. visa policy permits citizens of certain countries to travel to the U.S. without a visa under the Visa Waiver Program. Currently, 35 countries participate in the VWP. As the entry requirements...
In case of Emergency, dial 911 from any phone (public phone, hotel phone, etc…). It usually works with foreign cell phones as well, but you may want to confirm with your local cell phone...
Phone
Most international mobile phones work in the U.S. Check with your local provider about International features and roaming charges prior to your trip.
Public phones on the streets are rare...