What is the quickest way to level up?

What is the easiest or quickest way to level up? I'm a level 8 and Ive done all task and got thousands of troops. But I don't attack people. What should I do attack plp or what?

Attack forts and gather resources, make lots of troops and constantly have buildings being upgraded

Attack forts other playes?

Attack unoccupied forts, so you can take the resources