You can make your empire look like this within the first couple of turns:
http://i.imgur.com/Cw1GJcQ.png
Siege Cair Andros with Faramir in the first turn, siege E. Osgiliath with Boromir. Move your armies in the middle part of your realm southwards to take that settlement Harad gets. Move the garrisons from the western settlements to that western rebel city. Optionally use a boat to move the forces from Dol Amroth to that island, and send a couple of units to Druedan Forest.
After these initial landgrabs, the real war begins. Prepare to fight stacks coming from the Black Gate, Minas Morgul and Harad. Remember that around turn 15, the first Strong Mordor stack will spawn! It is vital that you keep the pressure up on Harad, you cannot fight both Harad and Mordor once they start to go on you at full capacity.