Take college classes. Baker College, Delta College, Grand Valley State University, Kirtland Community College, Lansing Community College, Macomb Community College, Mott Community College, Northwestern Michigan College, Oakland Community College, Oakland University and the University of Michigan all offer sign language classes. Some offer degrees in interpreting. Talk with students and sit in on classes to see if college ASL instruction is right for you. If it is, research which classes best suit your budget, schedule and location. If you want to become a professional interpreter, get a degree. However, if you just want to learn ASL, take a class or two as a non-degree student. (To learn more about each college's ASL program, visit their website and search for ASL in their academic programs.)
If college doesn't work for you, take a class from a different source. Deaf and Hard of Hearing Services and Sign Language Services of Michigan both offer ASL classes. Unlike a college, however, these groups cannot give you accreditation. Learn ASL from them only if you do not intend to become a professional interpreter.
Periodically search the Internet with phrases like "sign language classes in Michigan," as new courses, programs and teachers are advertised regularly. Be specific in your search if necessary. For example, if you have a baby who is hard of hearing, typing in "baby sign language classes in Michigan" can lead you to Babies and Sign Language, a website dedicated to listing ASL teachers who specialize in infants and toddlers.
Ask local university ASL professors and sign language offices about ASL conversation groups, even if you're not signing up for classes. They might be able to direct you to casual groups that meet to practice ASL, or introduce you to a conversation partner for extra practice.
Search the web for "online sign language" or "online ASL instruction" to find instructional websites. Determine if you have to pay before signing up for courses.
Visit an online bookstore (or a local bookstore, though they may not have as much choice) and type "ASL" into the search box. Choose books or software, or both, to study with.
Watch videos at sites like YouTube. Search for "basic sign language" or "learn sign language." If you have an account, save the most useful videos in your "favorites" file; if not, bookmark or somehow make a note of them so you can go back and use them for review.