This. There should be a website to tell you the "dos & don'ts", like whether or not this court will allow you to have a cellphone. If you can, be sure you turn the ringer & buzzer off.
And remember, it isn't about guilt or innocence - it's about whether the prosecution can prove their case.
Edit - you will be asked questions by the Attorneys & Judge (before you are seated). The big one is, if you were the lone dissenter in the jury room, would you hold firm if you were convinced in your belief of guilt or innocence? (see the movie "12 Angry Men" - essentially, could you be Henry Fonda's character & hold out?)