A clever strategy for capturing high level valleys is to allow your enemy to capture a high level valley first. Then you attack it and capture it after he recalls his troops. For example taking a level 10 valley will require 20k troops or more. However if you wait for an enemy to take a level 10 valley then you try to take it from him, you might be able to take it with only 1 troop! You can only do this if you are out of beginner’s protection.
Beginners Protection (BP) lasts for 7 days. UNLESS you cancel it. One way to cancel BP is to build your town hall (TH) to level 5. As soon as your TH is level 5 your beginner protection will end. If you cancel BP then you can attack and be attacked by other players.