Nah, seriosuly though I don't have very many sneaky moves on my account, I'm very much a blunt and repetative player: take that - build up - take that - build up - repeat.
A move I frequently use is simply emptying a few provinces to invade a neighbouring province. My force now gets so large that the enemy retreats. I can then recall most of the army to defend my other provinces and lure the AI to counter-attack my seemingly weak force. This tactic works excellently as long as your troops are superior to the AI's (which they are). Not very sneaky I know, but that's as good as it gets in my case I believe.
A variation of the above tactic that is very useful when fighting a superior enemy (I mostly experience this as the Poles or Huns against the Cumans in XL) is invading a weak perimeter province (in my cases mostly Moldavia), then leavy only a token garrison. Lure the main AI army from it's teched-up base province (Levidia in this case), then just raid that province (by sea if I'm playing as the Huns) and thereafter make for a swift retreat. It's basically the British tactics developed after WWI: destroy the production capability of your enemy.

Come to think of it, the only really sneaky move I can think of was more luck than anything else. In an Hungarian campaign (ages ago, it's in the Pics & history of your empire if anyone's interested) my neighbours, the Turks, had suffered a civil war and suddenly the Sultan and all his sons were isolated in Constantinople (only Rum remained loyal apart from Constantinople). I of course took the bait, got the Sultan as he fled and received plenty of cash.