Do not forget to take up the offering. If a church member waves a check at you, consider that you may have forgotten.
Take all food offered to you. If you have a new or newish car, please do not bring home a crock pot of hot soup. Just don't.
If you forget where you are in your sermon, you are in trouble. Look down at your outline and begin praying.
Even if the Holy Spirit is watching your back, wearing your chasuble inside out will show.
Pick a few hymns the congregation knows. Just a few. No one is asking you to be perfect.