Consider the financial and emotional changes in your household which will occur if you host a foreign exchange student. Taking in a student requires you to feed an extra mouth and to make space for another person in your home. Whilst neither need to be dramatic changes, thinking about the ramifications beforehand can help avoid potential problems.
Speak with your local school to see if they run an exchange program that is looking for host families. If your children's school runs a program, find out which teacher is in charge, and offer to be a host family. Even if your child does not participate in the exchange program, they may still need hosts.
Check to see if there are any exchange programs in your local area which need host families. "ASSE", "International Student Exchange" and "AFS" (see Resources) are all major exchange programs which may require host families. You may have to meet with the program director and submit your home to a cursory inspection.
Host a foreign exchange student, including him in your normal family activities. The purpose of a foreign exchange is to improve your language abilities and learn about a foreign culture. When the program is over, speak to the program director and tell him you would be prepared to do it again. Once the director knows you are a reliable host family, they will be happy to use you over and over.