You have to show up on the day they call you. Then it is all about establishing conflicts. Once you are sent to a courtroom, they will tell you what the case involves. Then they will ask you to think about similar experiences you may have had. This is where you build your conflicts. With a little creative thought, you can easily come up with tales from your life that would make you look prejudiced.
They asked my mom if she had any thoughts about motorcycles, she said "Yes, they kill teenagers"
One girl in my group pulled an Allie Sheedy from Breakfast Club. She stood up with hair in her face and a black trench coat on(in santa monica) and said "I am going through a lot of intense personal problems now and am in therapy and can't even focus on my own life, much less someone else's"
My case involved a landlord/tennant dispute and I told them about a landlord I had who sold my building while I was away and I came home to find the locks changed and my stuff stolen.

The most important thing is NOT to say anything about being too busy or unable to serve. They jumped all over a girl in my group who said she couldn't arrange travel to and from court. Another started in about her work schedule and the judge snapped at her about penalties to employers and civil duties. They get pissed if you seem like you are not willing to serve. They have to reject you.

Mine was in Santa Monica and it was a nice day. I watched people squirm, had a 90 minute lunch break on the 3rd street promenade, sat in the back of the court and waited to be questioned about the landlord thing. Then I spun my tale and sat back down. I was eliminated in the second round.