Group projects are a microcosm of life.
You probably won't be the smartest in the group or the dumbest in the group or the leader, but to be successful, you need to figure out how you can help the group be successful. If that's not possible, you have a more difficult task. You need to isolate yourself from the group's failure or try to make yourself appear successful, given the limitations of the group. Politicians have become masters of the latter, taking credit for their group's success and isolating themselves from theirs group's failures.
I found it helpful to think of group projects as an exercise in gaming the system.
Subconsciously, that's what most of the other players in the group are doing anyway. The dumb alpha guy wants to lead and won't listen to the smart girl. The smart girl gets frustrated and withdraws. The rest of the dumb guys just want to do as little as possible while someone else does the work. The smart geek has the right idea, but he doesn't have a clue how to present it to the rest of the group.
Remember, this is all happening somewhat subconsciously. By consciously remaining aware of what they are doing, you're in better position to consciously game the system. You can't push your ideas through, but you can quietly build a coalition with the smart girl and geeky guy and when the time is right and the alpha guy finally realizes his approach is going to fail, YOU can present their ideas. You don't have to worry about the losers. They just want to get a passing grade.
Now, if one of the losers is also the alpha, you've got problems. Welcome to the world of business!