Avvo is a good start. Type the city where your friend is located and review the results. I would next encourage you to check with local bar organizations within the area your friend lives. Visit the attorneys' websites and check on their expertise. Avvo may give you the most information about attorneys and you can review their expertise looks and the questions they have responded.
Aside from location, always check their license with the California State Bar. Good luck!
Since Immigration is now centrally filed (that is to say, all family related visa petitions are filed in Chicago, Illinois), any immigration attorney can give you assistance with your immigration matters. I am an attorney licenses both in Illinois and in California. 60% of my practice is in family law (divorce) matters and about 25% of my practice is with immigration. I am a member of the American Immigration Lawyers Association (AILA) a national organization of immigration attorneys. Since you did not ask a specific question, it is difficult to respond. My office does give a first time free consultation. www.BlairGreeneLaw.com.