Player movement help!

I am making a third person RPG and I need my player to move. I have made several different movement scripts, all with their own problems. My current one uses a rigidbody but makes the player constantly slide across the terrain. This is the code.

 public float speed = 300.0F;

 private Vector3 movement;
 private float rotationDirection;
 private Vector3 movementDirection;
 private float v;
 private float h;
 private bool dead;

 void Update() {
     StatManager statManager = GetComponent <StatManager> ();
     Respawn respawn = GetComponent <Respawn> ();
     CharacterController controller = GetComponent <CharacterController> ();
     Rigidbody rb = GetComponent <Rigidbody> ();

     dead = respawn.dead;
     speed = statManager.speed;
     h = Input.GetAxis ("Horizontal");
     v = Input.GetAxis ("Vertical");

     CheckDirection ();

     if (!dead) {
         move (h, v, rb);
     }
 }

 void move (float h, float v, Rigidbody rb) {
     movement.Set (h, 0f, v);

     movement = movement * speed * Time.deltaTime;

     rb.MovePosition (transform.position + movement);
 }

 void CheckDirection () {
     if (h == 0 && v > 0) {
         rotationDirection = 0;
         movementDirection = Vector3.forward;
     }

     if (h > 0 && v == 0) {
         rotationDirection = 90;
         movementDirection = Vector3.right;
     }

     if (h == 0 && v < 0) {
         rotationDirection = 180;
         movementDirection = Vector3.back;
     }

     if (h < 0 && v == 0) {
         rotationDirection = 270;
         movementDirection = Vector3.left;
     }

     if (h > 0 && v > 0) {
         rotationDirection = 45;
         movementDirection = new Vector3 (1, 0, 1);
     }

     if (h < 0 && v < 0) {
         rotationDirection = 135;
         movementDirection = new Vector3 (-1, 0, -1);
     }
     if (h > 0 && v < 0) {
         rotationDirection = 225;
         movementDirection = new Vector3 (1, 0, -1);
     }

     if (h < 0 && v > 0) {
         rotationDirection = 315;
         movementDirection = new Vector3 (-1, 0, 1);
     }

     transform.rotation = Quaternion.Euler (0, rotationDirection, 0);
 }

}

Could you please help me improve this code, either by fixing the sliding problem or proposing a different method. Thanks in advance