Display Press E to Pickup when mouse over object

What you could do is either a OnMouseOver(){} void or function and the script must be added to the pickup object. Or you could use vector3.distance to make it that you pick it up when your near(Note: this will not use direction so you can pick it up without looking at it). I would go to the unity3d script reference and look up these two things, but they will not be great but its pretty hard to make it work perfectly.

 var Highlighted : boolean;
 var ChosenColour : Color;
 var PickUp : String = "This Cool Thing Im Looking At";

 function OnMouseOver(){
     transform.renderer.material.color = ChosenColour;
     Highlighted = true;
 }

 function OnMouseExit(){
     transform.renderer.material.color = Color.white;
     Highlighted = false;
 }

 function OnGUI(){
     if(Highlighted == true){
         GUI.Label(Rect(Screen.width/2,Screen.height/2,200,20),"Press E to Pick up "+PickUp);
     }
 }