"Spend 80% of your time sharpening the sword and just 20% on the actual cutting process." This mantra holds good for successful project managers and development teams too. Statistics reveal that most of project fail in building value as a result of poor definition of requirements.
Before the commencement of the project it is imperative that team members understand the user requirements completely .Involve end users or Project owner right from initial stages. Getting the software users to talk to developers will ensure that interfaces, business analysis gets translated as code seamlessly.
Defining business requirements is considered a critical factor in the success of a project. Involving the users also helps determine the priority of the requirements thereby bring clarity.
Solid requirements planning help build connection between business case, project goals and the end result. Project managers always need to align their work towards creating intrinsic value for end customer. For a customer it is a healthy ROI. Successful projects not only leaves a happy customer / patron it impact the top line growth and leaves team morale on a high.

So how do you go about it ?
K.I.S.S (Keep it Sweet and simple). Have absolute clarity while capturing the requirements with end users. Use mind mapping tools to capture parent level requirements and child level requirements. Document the requirements into a concise document and get it reviewed with the customers.
Avoid the romanticism of trying to reinvent the wheel. Be clear in capturing the business environment into the document.The requirement document is so vital that it sets as a base for building the Statement of work and related estimates. So it is so crucial that we get this activity right !