Let me start by saying that this answer truly depends on what tradition you choose to follow.
That being said, I have ALWAYS lived by the belief that intent is the only true importance. Your craft does not need the most expensive or elaborate items to be successful. You need a clear intention and the right amount of concentration.
The magic is in you, rather than inanimate objects.
I have had sucess using a white candle for a money spell or a purple candle for cleansing. As you prepare your items, don't be afraid to tell them what their job is meant to be. Anoint the white yarn or cord and say, "You're to be used for this specific purpose. I know you'll serve my purpose."
Above all, have faith in yourself friend.
In Love & Light
-Chell