Just jamming to off the wall stuff is a very productive tool.
Everyone is going to want to do different things. Mabey you need to have a band meeting about what each member is interested in getting out of a band. All members need to be clear about what is most important to them to get out of a band. Out of all the things that you and the rest of your band will be wanting to do; surely there is one goal that you all can agree on. Set aside all other goals for now and focus on reaching that goal.
For example lets say that all of the members of the band want to get more attention from chicks by being in a band. Find out what music chicks at your school like, and as a band create a set based off of that information. From that point you will have a healthy band, and cohesion.
Bass guitar is the answer to everything