Cover the entire bulletin board with blue paper and scatter green lily pad cutouts throughout. Add a banner reading "Jumping into Pre-K" and some paper frogs and insects, if you have them. Place a picture or drawing of each student on a separate lily pad with the student's name attached.
Decorate the bulletin board with a row of train cars along a track. Put the students' names and/or pictures on each one. The locomotive could feature a conductor and display the teacher's name. Spell out a phrase such as "We're on the Right Track" or "Friendship Train" to frame the train cars.
Create a simple street scene -- possibly with some trees and clouds -- and hang a large school bus made of black and yellow construction paper. The students can bring in a photo from home or draw pictures of themselves to place in the windows of the school bus. Write the name of the school and principal along the side.
To help loosen nerves and get things started on the first day of school, have each child draw a simple picture. It can be a picture of anything: their favorite food, an animal or a smiley face. Display all of the drawings on the "Art Museum" bulletin board along with the students' names. Make the board resemble a museum by including paper frames around each drawing.