Prepare your resume. Even if you do not apply for a paid job, most positions require a resume. Make sure to include your relevant legal experience, even if it does not directly involve family law. In your "objective" section, be sure to state your passion for family law.
Send your resume. You can apply as a legal assistant in a family law office. You can also apply as a paralegal. As long as you get your foot in the door, your experience will grow into hands-on meaningful experience over time. You can find job postings online or directly through your law school. If you cannot find a posting, send your resume and cover letter to family law offices in your area. Do not give up until you secure an interview.
Attend an interview and secure a position. Take the opportunity to work at a family law office to ask constant questions of real family law practitioners. Try to attend real court cases and observe the arguments on either side. Over time, you will become immersed in the family law experience.