This is based upon first understanding the expectations of your client and what they are hoping the project will deliver. However these expectations may be unrealistic - they do not become the project outcomes until you agree with them.
In what way might your client's expectations be unrealistic? ......
Sometimes, they want things done quicker than what is possible, given the resources at your disposal. Other times, they don't have the budget to accompany their high expectations.
So as a project manager you need to be able to manage client expectations - and this means you must be assertive. In a pure environment, the project timeline, resources and budget are determined by the goals of the client. But often in the workplace, there are constraints which influence the ultimate scope of the project.
Invest the time up-front in understanding what the client wants to achieve with the project - but make equally sure that you discuss any possible constraints (for example, the number of staff that can be released and for how long, and with what skills) before you commit to an agreement on project outcomes.
Your reputation and future credibility will only become tarnished if you over-promise and under-deliver! And also ensure that once the project outcomes are agreed together with the associated budget, resources and timeline - that this is properly documented and signed off with your client.
You have a record of the project scope that will help prevent later misunderstandings. This is now the foundation on which the project will be constructed.
In closing, if you are seeking some training in project management, have a look at Project Management Courses Melbourne - short one and two day in-company courses that offer tips and tools for the new project manager. Another useful course that is delivered in-house is MS Project Training, in case you are not completely confident with this software
