Before embarking on the development process, you should have a clear idea of what your workflow and final product should look like.
Make sure that all of your team members are very clear on the requirements.
Faulty division of labour
There should be no confusion amongst your team as to who is responsible for what tasks.
Lack of communication
There should be transparency on the progress made by each team, the obstacles they are facing and the resources required to overcome those obstacles.
Not taking heed of feedback
Critical feedback is not easy for any developer to hear. But, taking cognisance of and incorporating this feedback into the process early, will save you a lot of pain down the line.
Taking testing lightly
Software testing is critical at both the inception and culmination of the development process.
Forgetting to comment on and structure code
Structuring and adding comments to code is another seemingly tedious and often overlooked part of software development.