Smooth movement

How could I make my character move forward smoother?

So that it takes a while until the character is moving full speed and also takes a while to stop.

This is my current code for moving forward.

    // WALKING
    if(isWalking == true){
       transform.Translate(Vector3.forward * Time.deltaTime * walkSpeed);

You could try linear interpolation:

if( isWalking ) {
  currentMoveSpeed = Mathf.Lerp(currentMoveSpeed, walkSpeed, smoothTime * Time.deltaTime);
  transform.Translate(Vector3.forward * currentMoveSpeed * Time.deltaTime);
} else {
   currentMoveSpeed = Mathf.Lerp(currentMoveSpeed, 0, smoothTime * Time.deltaTime);

we are interpolating between the “currentMoveSpeed” and “walkSpeed” to smooth the beginning of movement and from “currentMoveSpeed” to 0 to smooth the end of movement. “smoothTime” would be the variable to control the acceleration (in units per second).
Hope this helps!