Getting called for jury service is random I believe.
Once you show up, they pick about 80 people and you walk into the room. The judge and lawyers relay the case to all the potential jurors and then ask questions to about 5 - 20 people at a time to determine whether or not you'll be good enough to serve on the jury. Questions like "have you been a victim of this particular crime?", "do you have family in law enforcement?","do you distrust authority figures?", and even your opinion on certain issues (such as guns or abortion). They do this to weed out any potential jurors who have bias, in order to try and create as fair and unbiased jury as they possibly can.
A jury has to be narrowed down to 12 people out of 80, so depending on the people, things can go fast or slow.
If you have opinions or experiences that the judge or lawyers might deem as making you too potentially biased, you're dismissed from jury duty and won't have to report into jury service for another two years. Also, they might not even get to you and decide to stick with the jury they've decided, so then everyone else is dismissed and doesn't have to show for jury service for another 2 years - which is what happened with me; and I was thankful for it, because frankly, I didn't want to be there at that particular time.