First try to find between what hours, the player which you want to attack is active, from which country is and between what hours he sleep.

You must try to send the attack when the defender is not on-line.

Lets suppose that you want to destroy from one town all the crop fields and 2 granary.
If you have rally point at level 20 you can send 4 double attacks with cata.
First we will send the same number of fakes attacks on other 4-5 towns of the enemy.
The defender could guess in what town he will be attacked and even he has time to bring enough defense from his alliance, he could try to bring defense after our clearing attack.
For this we put in front of our real attacks 2 fake attacks with one catapult. In final we will have 6 attacks on each of his target villages.