Where I live:
They use the lists of registered voters, lists of holders of drivers’ licenses or ID’s issued by the Division of Motor Vehicles, lists of state tax filers, and recipients of unemployment insurance or family assistance, to randomly select people for jury duty.
You can request to be excused based on financial or medical hardship, but you have to back it up with documentation. You can also request a postponement once, but you must give an alternate date, which falls within 2-6 months of your jury notice, when you will be available to serve.
If you do report for state jury duty, you are not eligible to serve again for six years. If you served for 10 days or more, you are not eligible to serve again for 8 years.
If you were called for state jury service, you can still be called for federal jury service after a period that varies between 2-4 years.
The last time I was called for state jury duty, I was on telephone standby for about 2 days. So, I didn't have to show up at the courthouse, but I did have to call in at a certain time each day to find out if I was required to appear. On the 2nd day, I was told to show up. I think that standby status can go on for 5 days, and if you don't have to physically appear by then, you are excused, but you are considered to have fulfilled your jury service. Using the telephone standby method probably does cut down on the days you spend just sitting in the courthouse waiting because they can have blocks of potential jurors show up as they need them.