Go to your high school or university's study abroad office. Get a list of the possibilities and all the information you can pick up. Emphasize your field of study and (if applicable) any foreign language skills you already have.
Get online and use the information obtained at the study abroad office to contact individual providers of study abroad programs. Look through the information and pick out a few programs that look interesting to you.
Go back to the appropriate office at your school and see which of the programs you selected can be pre-approved by the school for participation and - most importantly - academic credit. You don't want to study abroad for a year and then find out your credits cannot be used toward graduation or your major.
Consider the costs. These prices vary depending on where you go, how long you stay and who is administering the program, but you need to consider all of the costs of the trip and make sure you can afford them before you apply.
Find students at your school who have recently returned from the study abroad program you are considering, or go online at one of the study abroad sites. Discuss the pros and cons of each program with people who have experienced them.
Weigh all the issues and apply to the program that best fits your needs.