No big deal. Have both vCenter Server's vSphere Client connection in place, create the datacenter/folder/cluster structure you want in your new vCenter.
Disable HA/DRS in the old vCenter Server's clusters. Select hosts one by one in the old vCenter, right click, remove.
Go to new vCenter Server, configure cluster settings, right click cluster, add new host and voila.
Repeat the steps until you complete building your environment.
Finally check for any additional plugins you need to install/enable in your new vSphere Client.