While using a emoji may only have a small effect, try using it when you win ONLY. This puts the opponent on tilt and may help you get a bit more out of them if you have a big hand.

your competitors don't always see emoticons some of them have this feature disabled

I don't use anything except my game...

I just disable my chat altogether and focus on the game itself!

I usually have number of players and my position on display . Fire away emoji's