I know the movement for Tango should be sharp and quick. How can I make my movements be more sharper? Are there exercises/tips that will help?

Also, I want some tips about the facial expression as well.

Thanks in advance.

Babyruth. As one writter said. To instruct in writing is like learning to play the piano over the telephone. It can't be done. An easy one to correct though would be the facial expression. Dont smile. Also Tango is a walking dance. The feet are not skimming the floor as in the Foxtrot. The movement across the floor should be absolutely silent, no foot noise.I doubt if anybody ever learnt to do this dance correctly without lessons.The other dances should be learnt first.

Ironically, Scriv. believed that Tango was the easiest of the 4 to learn...

I agree that in many ways Tango is the easiest of the Ballroom styles to learn, mainly due to the lack of swing from the hips in the walking action, which beginners, in particular, find so difficult.

One of the key 'style' features of the walk (and therefore of the character of this 'walking' dance) is the rapid foot movement. When walking, delay the movement of the standing foot for as long as the music will allow, before bringing the foot to its new position, sharply.

In the swing dances, we tend to time the swing of the legs evenly, just like a pendulum, and if we danced tango in the same way, counting as we went, we would place the first step on 'One' and start to move the other foot on 'And', before placing it on 'Two'. But this is Tango: try placing the foot on the beat, but not moving the other foot, at all, until you have sounded the 'D' in the counted 'And'. That will give you something like the required timing.

Lets look at the problems that face learning the Tango correctly for the first time. Most likely the candidate has learned the Waltz and Foxtrot first. Now they have to learn that in the setup the lady is more to the mans right side. The hold is entirely different. The feet are off set and if they are pointing diagnal to the wall the body is turned 1/8 anti -clockwise. the knees are veered into each other, because of this the dance has a curve to it, also anti- clock. Also in a Walk the first step on the Left foot is in CBMP. To close. If none of this is explained from the very beginning the teachers are taking money under false pretences.I think when Len Scrivener was suggesting that the Tango Steps are easy to learn he meant that it would be simpler to teach the steps Two Walks and a Progressive Link than it would be a Natural Turn in the Foxtrot. But to do the two Walks and the Progessive Link correctly thats a different story.

I wonder if you have seen yourself on video? Or been told your movements are not sharp enough? You need to avoid the "cat shaking a rat" type of movement, make your stops and turns crisp and well defined (don't overshoot and pull back to try to improve the sharpness). I think a lot of the sharpness in tango movements is an illusion in the viewers eyes, their brain expects you to continue in the direction you are moving, a sudden stop or turn will register very sharply. Remember the shot towards the end of "The Graduate" movie where Benjamin is running towards the camera on a long telephoto lens? When he changed direction and turned right into the church path, the effect was amazing.
Facial expression should also be natural, just a bit serious as the dance is a play between the man and woman. I was told your eyes never meet as you would typically just spent 6 months on the ranch and not brushed your teeth during that time!
Remember the lady has to follow the man, so don't bruise her!