There is no magic or mystery, just a lot of hard work. Most people are too lazy to get good.
It isn't the number of years you have practiced but the number of hours you have put into those years.
If you want to learn to punch, you must punch a lot. If you want to learn to kick, you must kick a lot.
The key to making Wing Tsun work is the footwork. Therefore every practice should involve shifting (turning), and stepping footwork.
The proper Wing Tsun stance has 100% of the weight on the rear leg. The pelvis is tilted in. The front leg is springy and can't be swept. The knees are close so that a kick can't get in. (this was the forward stance description).
Getting into kicks is a matter of timing, which comes from a lot of practice against kicks. Start with the easy ones.
Wing Tsun does not use the backwards step. Stay there, go forward, or turn.
When a force comes, we don't interfere with the path of that force. We use a swift intercepting force and turning of the body to neutralize the force. The second set of Wing Tsun teaches the appropriate footwork. The direction you turn depends on the direction of the force.
You don't plan which action you'll take. You have to feel how the force is coming. Imagine a stick floating down the river and that stick hits a rock. The stick will get deflected in some direction which could not be predicted beforehand. Similarly when a punch comes in, we receive that force and that force makes our body react and change to an appropriate Wing Tsun structure like Bong sau or Tan sau.
Wing Tsun has no blocks or deflections but only temporary transition points. This Bong sau only occurs for an instant and then changes to an attack.
When you punch, you relax everything so that eventually you can transmit the power from the ground and all the joints in your body to your fist. As soon as you tighten something, you are blocking power.
The showmanship one inch punch sends you flying. The real one inch punch will drop you on the spot.
Don't forcefully deflect punches with the Bong sau or else you are doing Karate using Wing Chun shapes.
To learn feeling, one partner feeds the other force, then they react with Bong sau, Tan sau, Fook sau, Chum sau etc.
The arm is like a spring with the same pressure always. If you push on the Bong sau, you are compressing a spring. When you release the pressure, the spring snaps into your face.
Every kind of strike is powerful in Wing Tsun.
Once you attack, there are fists, elbows, knees, ... everything comes at high speed.
You need an organized training system or else little progress will result.
The Wing Tsun system has numerous innovative training procedures which slowly bring the student up to the level of being able to handle any of today's styles of martial art. But again it is the students hard work and not some secret techniques which brings results.