It’s almost impossible to stop other players from earning crowns at all against you, because practically all that they have to do is destroy one single tower. You can stop them from earning three crowns, though. One good strategy is to pick one single place in your road, then curve it, and load up all of your barricades and towers in or around that one spot. They’ll rarely get past that in one piece, and if they do, their time will run out while they are attacking your castle gate.
Another simple strategy is simply to stuff a ton of towers around your castle, and use barricades and spiked platforms earlier in the path to shut down your opponent. Usually, then, they will try to attack your castle and ignore the defensive towers, but in doing this, opposing players will end up missing out on one or two crowns.
When you’re attacking another player, have your player stand right in front of the spiked platforms, and he’ll attack them automatically. Don’t have him walk on the platforms. Your soldiers will, of course, automatically walk on the platforms, but try to destroy them as soon as possible in order to save your soldiers from getting mauled by them.
Food runs out extremely quickly, and you won’t want to waste all of your extra gems on topping off your food. The FIRST thing you should upgrade after finishing the upgrade on your throne room are your farms. Upgrade your silo too if you need to, but if you battle a lot then you shouldn’t. Taverns, consequently, are about the last thing you should upgrade, considering you earn a ton of coins just by battling.
Wanna find easier battles? Each time that you go to the battle mode, hit the “next” button if the proposed opposition’s paths are too twisted and too full of barricades, towers and other obstacles. Keep hitting next until you come across an easier one, and they’re plentiful, because LOTS of players totally neglect the defensive portion of their kingdom.
Do the same thing if you want to earn more coins, trophies or medals for a battle. Just hit the next button til you find one with a high payout.