The key to delivering a project that a client is truly satisfied with comes down to 3 constraints: Budget, Schedule and Scope
Not all of these constraints may be within the control of the project manager, for example, there may be a pre-defined schedule designed to meet some inflexible market-driven deadline. But providing the project manager can control at least one of these constraints then being unable to control them all will not prevent the successful completion of the project.
The way in which an experienced project manager will tackle such a project is to manipulate the constraints over which he does have control in order to satisfy the remaining constraint(s). So if the schedule cannot be altered because of an immovable deadline, then the scope can be adjusted to deliver all the fundamental requirements of the client without, say, some of the desirable but unnecessary features. And if the budget has some flexibility then additional staff could be employed to meet the deadline. (Although, purely throwing money at a project never tends to work, in my opinion).
The projects doomed to failure from the start are those where the constraints of budget, schedule and scope are either all outside the control of the project manager (in which case you have to wonder about the job description of that poor guy) or are all totally unrealistic (ditto).
So how should you decide which constraint to target for changing?
As far as the budget is concerned you should obtain realistic estimates, and hence total costs, as soon as possible so that any additional funding can be requested as early as possible in the planning stage. If costs have already been established from well-researched estimates, it is unlikely that substantial budget increases will be forthcoming.
As far as the schedule is concerned there are many factors that can influence pre-defined deadlines – this could be a market-driven deadline such as being the first company to bring a product to market or producing an equivalent product to a major competitor. It could, alternatively, be a response to an influential client and the desire to produce high levels of customer satisfaction. Whatever the situation, make sure you understand exactly what the priorities are of both the client and senior management with respect to deadlines.
As far as the scope is concerned it is critical that the project manager fully understands the priorities of the client if the requirements are to be modified to fit in with a pre-determined budget and schedule but still deliver an acceptable product. And remember that determining priorities is not just about finding out what senior management perceive to be of the highest priority – also talk to the end-users who will always have insights on how a product or system can be used to best advantage. Features that are categorised as the lowest priority can always be scheduled for a later date once the core deliverable has been completed successfully.
Successful project management is delivering the right product, at the right cost, at the right time. So all you, as a project manager, have to do is determine the definition of “right”.