Pick the show you want to attend and the dates you'll be in the area where it's filmed. Los Angeles and Hollywood are still hotspots for most sitcom studios. Filming takes place on weekdays and the filming season has become almost year-round, so there's a good chance something will be in the works during your visit.
Find your tickets online, preferably several weeks ahead of time. There's no single website that distributes tickets for every sitcom, so you may have to visit several before you find the show you want. When you do, just print the tickets out and bring them with you. Some shows have tickets or empty seats available up to the last minute, but if you're picky about what you want to see or have traveled a long distance, then it's better to get them in advance.
Show up at the studio early. Audiences are always overbooked to ensure there's a full house for the taping, so if you have tickets but show up late, you might not even get in. The call time, which will be on your ticket, is when the audience is expected to arrive and get in line, but try to arrive even earlier. The more popular the show is, the longer the line will be but expect to wait in line for an hour at the very least.
Remember that the filming for a 30-minute sitcom takes much longer than 30 minutes. Usually it's closer to 3 hours or even longer, so plan on the whole process taking up most of the day.
Don't bring your camera, cell phone, food, young children or items that could be interpreted as weapons. You can eat while in line, but not in the studio. The ushers won't hesitate to ask you to leave if you're making noise or other distractions so leave your gadgets in the car. Most studios have minimum age limits of 16 or 18 years old, but some game shows and Nickelodeon shows allow children 8 years and up.
Follow the directions you're given and you won't have any problems. Don't wander around the studio, or run off to find the cast members, as you probably won't make it very far before the security guards take you down. Seats aren't assigned but you'll be directed as to where they want you to sit. Before the show starts there will likely be a warm-up act of some kind, like stand-up comedy to get the audience in shape. The filming won't be at all like watching TV. In fact it ought to be much more fun since it involves a lot of retakes and set changes, and you'll get to see how your favorite celebrities act in real life.