I learned during my last internship about some of the things that should be put into consideration before deciding on deadlines. For example, inaccurately defined deliverables, omitted deliverable documents, avoiding informal agreements, never make assumptions, everyone needs to pull their own weight, deliverables have dependencies, and always think about additional project deliverables factors.
Inaccurately defined deliverables are one of the biggest risk factors when it comes to project success or failure. Many companies have suffered the consequences of missed objectives and deliverables simply because of a lack of clearly identified or defined intangible and tangible deliverables at the onset. Having a vague understanding of project and client needs or company direction is usually at the root of most unsuccessfully identified deliverables. Project managers should slow things down enough at the beginning stages to be able to accurately gather all pertinent information from key stakeholders before charging ahead.