To earn points simply stop as many Creeps as possible from invading the Kingdom In the same way, stopping stronger creeps will award you with more points and elixir.
The stronger the Creep you defeat the more points you’ll be rewarded.
The wave indicator, which is the skull icon in the top left hand side of the screen will show you your current multiplier, which will affect the points you get from each Creep.
Therefore, the longer you hold of the creeps the harder it will become and the more points you will gain. So, hang in there!