Aside from the battle points, you can get loot too. Attacking for resources is called farming. Because flying myths are more expensive, I suggest using land units to clear away their land units. If they are not on the same island, send transport boats or fast transport boat to carry the land units and light ships to escort them. Your troops might die, but you will get battle points. However, some good fighters cannot carry a lot of loot. So after making sure the enemy's units are dead, you can send in more expensive flying myths to farm the resources. This way, they are less likely to die. However, if you find that you did not loot as much as you could have, sending in the farming units would be unnecessary as you probably already looted all of their resources that you could. And then, there are the exceptions. If you have a large dive bombing fleet, feel free to send them in waves at the enemy. You might loose some, but if you have a lot it will not matter. If you try an attack, and the report says that your ships were sunk by a large army of defensive boats, and because they occupy the area, they got lazy on land units, you might choose to only attack with flying myths because ships won't get through anyways. I like farming my neighbors for resources, but once you kill off their army, you only get resources and not battle points because you didn't kill any units. Attacking too often is useless because they don't have units for battle points nor resources to loot. And once you run out od pop, you desperately need cities, not resources. You should then keep on attacking different people, like they are on shifts. This way, they all have enough time to build up some units for battle points but not a large army that can wipe you out. They are very useful in organizing victory processions, which allows you to build more cities. If you are a gold spender in a world with no battle point villages, forget about battle points and farm instead. Olympic games are way better.
Just remember: ATTACK, BUILD, REPEAT