GetComponent

UsingOtherComponents

using UnityEngine;
using System.Collections;
public class UsingOtherComponents : MonoBehaviour
{    public GameObject otherGameObject;    
    private AnotherScript anotherScript;    
    private YetAnotherScript yetAnotherScript;    
    private BoxCollider boxCol;    
    void Awake (){
        anotherScript = GetComponent<AnotherScript>();
        yetAnotherScript = otherGameObject.GetComponent<YetAnotherScript>();
        boxCol = otherGameObject.GetComponent<BoxCollider>();
    }    
    void Start (){
        boxCol.size = new Vector3(3,3,3);
        Debug.Log("The player's score is " + anotherScript.playerScore);
        Debug.Log("The player has died " + yetAnotherScript.numberOfPlayerDeaths + " times");
    }
}

AnotherScript

using UnityEngine;
using System.Collections;
public class AnotherScript : MonoBehaviour
{    
    public int playerScore = 9001;
}

YetAnotherScript

using UnityEngine;
using System.Collections;
public class YetAnotherScript : MonoBehaviour
{    
    public int numberOfPlayerDeaths = 3;
}