In simple words: testing and tracking.
On average, I found 1 winners out of 7.

Talking about Copy a campaign...here are some food for though:

Copy a campaign could be tricky...

Personally I don't do a copy campaign method, simply because I will never able to know whether that campaign is a looser or winner.

Second, even if I copy the same campaign with the same keywords, your Adwords history will be a deciding factor whether your campaign will rank better than others that also bid on the same keywords as you do.