K.I.S.S. (Keep it Simple and Sensible)
Many teachers dread designing bulletin boards, because they equate the activity with having artistic talent. This is not accurate. Clearly, some teachers have some artistic talent and create striking bulletin boards. This is great, but, the truth is that a bulletin board need only be designed to reflect an objective or purpose. It should be simple, but in good taste, particularly in the hallways.
Most visitors to schools, unless it's an open house, don't have a great deal of time to stand and read confusing and over-worked bulletin boards. For the most part, at least in my teaching experience, visitors seem to have a "snatch and grab" mentality. They're busy and want to get the message fast and get to work or wherever they're headed.
Schools are for students, therefore, bulletin boards should be for students. Allowing students to invest in the design process empowers them. Isn't that what it's all about?