Leveling resources is about balancing resources' work distribution, starting with solving overallocations.
This split view (Gantt Chart in the upper part and Resource Sheet in the lower one) is giving information about tasks and resources in the same time, making resource leveling an easy job.
Basically, in Resource Sheet are visible resource-oriented data: working hours, assignments and issues indicated by colors. You will see overallocated resources (resources programmed to work on all the assigned tasks more than is possible, according to their calendars and MaxUnits values) marked with the red color and the resources that have overtime work (work scheduled beyond its regular working hours) marked in yellow. Also, the table indicates the assigned task and the time frame when the problem occurs.
Depending on the situation, there are a few methods to solve the overallocations:
1. Remove resources or decrease Units value for some of the resource's assignments until their sum does not exceed the MaxUnits value. If needed, available resources can be added (available hours are shown in green color). To do this in the current view select the appropriate task, open Details window for the lower pane, click Resources tab, and make the necessary modifications.
Hint: To keep constant the task work, before any assignment modification select Try to keep the work when changing resources/duration (make task work-driven) checkbox at the bottom of Resources tab. Hence the duration of the task will change automatically to match the work with the assigned resources.
2. Move one or more tasks, if you consider the lack of resources as a constraint. You can also link tasks that require the same resources, although is not recommended. In both cases a note on the task would be useful to remind you the cause of the action.
3. Increase the MaxUnits value (employ more resources with the same role), if the work has to be done in the scheduled time. In this case, the name of the resource should indicate a role rather than a specific human resource.
Hint: In Details window you can see resource/task details, depending on your currently selected element in the table.