Have a look at those (1st link has a section for DRS). For DRS if you have it set to manual, you'll have to pay attention to the recommendations. In my environment, for most of my clusters, DRS is set to auto with the default migration threshold.
http://www.vmware.com/pdf/Perf_Best_Practices_vSphere5.1.pdf
http://www.vmware.com/files/pdf/techpaper/vmw-vsphere-high-availability.pdf