Looting explained

As of 1.8, looting is based on castle level. So based on what was discovered.....

Castle Level Threshold
The level difference for looting now is 1, i.e. if I am castle level 10, I can only loot from castle level 9 and above.

However, this threshold only applies to players that are level 25 and below. If your opponent is level 25 and above, you will loot regardless of castle difference.

Telling castle level
There is no way you can tell a castle level from the city itself. However, look out for your victim's outposts. If he has an outpost that is upgraded to level 7, it means he at least has a castle level 7.

Crowns
Crowns can be obtained from raiding other players' city, outposts or heroes. As a rule of thumb, crowns looting is also pegged to the castle level threshold discussed above. In a nutshell, the amount of crowns you obtain are based on the following:
 * 1) The difference in crowns between you and your victim. If your victim has more crowns and you can loot him, you will gain a substantial amount of crowns after whacking him. As a gauge, someone with less than 100 crowns can loot 28 crowns from a player with 580+ crowns by whacking the hero.
 * 2) It was also discovered that you get more crowns when you managed to destroy a large chunk of the defender's forces.
 * 3) It was also discovered that hitting heroes will yield more crowns. If possible, hit heroes.

How much would my loot be?
Scout your target before you actually attack. The tactic screen will show the amount of loot you will gain upon wipeout (wipe out only.). Remember, you can only loot only when you win. There are a few kinds of victories, depending on the amount of power you decimate:
 * 1) close victory
 * 2) sweeping victory
 * 3) decisive win
 * 4) wipe out

The amount of loot you gain increases with as the level of victory goes higher. You gain the most upon wipeout. If the target has a lot of resources in all categories (Valorium, Crystals, Gold, Wood), you will most likely get an equal amount of each resource upon wipeout.

For example: Your current hero's loot cap is 100k and the target has 100k valorium, 200k crystals, 150k woods and 150k golds lootable. Assuming you are able to wipe him out in one shot and his castle level is same as yours, you will get 25k valorium, 25k crystals, 25k woods and 25k gold.

How to prevent looting
Basically, beside the tips from the other guide, one way to prevent looting is to maintain a relatively low castle level. Then try to loot as much as possible for your next main structural upgrade (Castle/Heroes Hall/Camp).

For example, your castle level is now 4, so you will loot the amount required for castle 5, heroes hall 5 and camp 5 before you proceed with your castle 5 upgrade. When your castle 5 is ongoing, try to loot as much as possible to make up the difference for getting looted. This way, higher levels might find it hard to loot you. Of course as you reach castle 7, this strategy might not be that viable anymore. Nonetheless, for low levels, you can consider this strategy for your saving plan.

Nonetheless, this method will only apply when you are level 25 and below, so you will have to make sure that your defence is rock solid by the time you reach level 26.