How do I best plan my resources with MS Project?

MS Project has resource planning capabilities. You can create a master list of resources for your project. Each resource can have a cost associated with it and a resource utilization. As resources are assigned to tasks, you can track if the resource is overutilized, cost allocation to the project and so on using the built in reports.

MS project is a tool, the benefits you get depend on your use of it

The allocation of internal resources.