[header] How to allocate resources in microsoft project [title] Consider resource availability when estimating task durations. [step] This step is crucial but often overlooked. Resources must be considered during the construction of the schedule, not just afterwards. 
Pay special attention to concurrent tasks (those that happen at the same time) that use the same resources. For instance, you might rightly assume that both the interior and exterior walls of a building could be framed at the same time.