The way I do it is become the Romans get my warriors and attack the greeks as soon as possible. Reason bieng is because the greeks are still building spear men and takes sometime. So you attack and you automatically get Greece without them doing anything about it. Next I usally attack the Zulu after building a barracks and start building spear men units as well. Afterwards I go on to conquer the world >:]
I finally got my first Domination victory today and I found, the Aztec and the Zulus are easiest to take out. Greeks should come first because they have a great area and they won't be able to even put up a fight.
If you are gonna take out the Greeks, I would be the Romans and rush to Mathematics. Then as quicky as possible get an army of Catapults with at least one other army to guard them.
Also don't just take the direct approach. In this weeks map there is a hill to the northwest of Athens. Launch your assault from there. And if you really want to maximize your chances, send a spy along with your armies to destroy their fortifications and/or disrupt defensive units.
Last night I got LUCKY and was able to sack Athens with a veteran warrior army from that hill. The first battle gave my vets an immediate upgrade, the second battle actually gave them a general (woot), I took Athens on the third turn of the assault. With Zimbabwe and Athens under my belt the rest of the game was a curb-stomp.
However luck like that doesn't come often. You need something to put those Hoplites and even then you need things like superior numbers, terrain advantages, and spies if you want your victory to be assured.