Tips and Tricks
When attacking castles assign a few ground troops as wellsince they can keep defenses off your back so your ballista can do hard-hitting damage.
Shoot more at the bottom of a castle you are attacking.
Boosters are time-based weapons that can clear the playing field for you and you'll get a free one-time use out of each one, but after that, you'll need to pay for more using gems that you collected.
Always take care your ballista first in between takes since it's your main line of defense.
If you can, try to score headshots on the soldiers.
Getting three stars every time should be a real goal as they open up bonus challenges where you can earn extra stars, as well as gold and gems.
If you need to purchase anything, go with the VIP package. This provides you with a few ample rewards per week for the same price, including various coins, gems and other goods. It's the best way to go if you prefer to spend.