For help with this, local department stores will organize a workshop for student clubs and maybe even a discount. Bottom line, you have to sound good and look good in the interview. Don't waste your time and energy. You'll be tempted to take every interview you're offered thinking that at least one of them will be successful. The interview is not just the 30 minutes of face time.
Many students find that the warm up worries and post interview agonizing consume the whole day.
If students have more than one interview on a day, they tend to project a tired, not a vital, personality. You might also maximize interviews for the practice. Don't waste the recruiters time and take potential spots from your fellow students. If you think you need practice interviewing, arrange informational interviews in which you make an appointment to get information about career possibilities. Most human resource departments will accommodate you, particularly during a slow season.