Keritot 6 - How To Improve One's Luck
Jewish kings were anointed near a spring, to symbolize that their rule would endure, just as King David said to his servants, "Take Solomon down to the Gichon spring and anoint him there."
We see thus that one can use sign, or omens, to influence his luck. For example, if one wants to know if his business venture will succeed, he can raise a rooster (who is quick and industrious), and raise him for the sake of his venture; if it grows plump and fine, he will know that he is likely to succeed. In the same vein, one should be accustomed to eat at the beginning of new year (Rosh HaShanah) a gourd, fenugreek, leek, beets, and dates, because these grow speedily and some are particularly sweet.
However, how do omens work and why is it not prohibited divination? The basic premise is that God wants to do good for men, thus, giving credence to a good omen is not divination but just confirmation of this intent. However, believing in negative omens would indeed be divination, and in additional would not be a wise things to do - for this may bring more worry to a person and lead to a weakening of his luck. That is why the omens above mention only the possibility of positive outcome.
Art: After Peeter Boel - A Rooster