SAVEN
When enemy is sending fleet against you can see that in “Overview” ( if your spy research is 8 or above you can see the exact number of ships that attacks you.
Pack all the resources you have (be sure you will left enough gas so you ships can lift off) in your ships 3-4 minutes before the enemy strikes you-send them to nearby planet(no matter witch) on mission Transport. After you are hit and you receive the report (not before receiving!!!!), go to Fleet menu and cancel the mission.
That is the way to save your ships and resource giving nothing to the enemy.
Long SAVEN
If the attack is after long period of time and you do not have the opportunity to be online and make saven soon before the attack-send the fleet on mission Attack on planet with (i)
NINJA
If you see an enemy attack advancing and you have enough ships to pay him/her a nice welcome, the trick is to hide them before the arrival of the enemy fleet. Otherwise your guest may see them and escape. You make a fleetsave as you calculate the arrival of your fleet up to 5 seconds before the enemy strikes. The is no chance for 5 seconds the enemy to spy and withdraw. It`s strongly advisable to ask somebody else to recycle for you or the attacker can guess your plan when he/she sees that your recyclers are gone. You MUST be online by the time of the attack. If you are not your fleet may not land in time but when the script lands it. This may happen 10-15 minutes after the enemy strikes and you can guess the results.