This is a decent start, but there are some minor things I would like to add
Don't sell all your defence, as it will leave you to vunerable to Anti-Covert Action against you. also, when setting up fr a war, you should move all available UU to either the Mines, or into Anti-Covert (Unless you plan on killing spies, it is best to the mines as you will need the extra income to repair with, and to expand your bank.
Lower you Covert Unit number to about 50K. this will be enough to keep the enimy from sabbing you to easy, but it is not enough to try to kill your spies...unless they are really bored
don't do anything to extreme, as sometimes things are irreversable.
If you have Anti-Covert agents, and you are prepareing to mass a defence down, Raid, don't attack, as raiding does not include Anti-Covert agents, and you also get the bonus of taking their UU and lessening their chance to rebuild as easily.
Use Defence Mercs as much as possible, these are relitively cheap, and can be bought on the market.
There is other things, I wil add them later as I think of them