Lead Hi, then low, to indicate a doubleton.
Second hand low, third hand high. If you play second, play a low card. If you play third, play a high card. At second hand do not think you must play high to "force out" a high card on the board. You do have a partner and the opponents do not know what you both have.
Lead THROUGH strength. If the dummy is to your left, your are leading through the dummy, i.e., the dummy plays second. Therefore, lead a card in the highest suit on the board, possibly forcing your opponent to play high second hand. Imagine there is a King, little on the board. Your partner may have the Ace, Queen. By leading through the King, your partner can make both the queen and the Ace
Lead TO weakness. If the dummy is on your right, you are leading to the dummy, i.e., the dummy plays last. Therefore, lead a card in the weakest suit on the board. This forces your opponent to play high second hand.
Honor thy Partner. If your partner had the opening lead or some other lead, when you gain the lead, return the suit that your partner led.
Cover an honor with an honor. If the person to your right plays a high card, usually cover it with a higher honor if you have one, even if it will subsequently be overtaken on the board. (Your opponents had to use two good cards to make one trick.)
Do not send a wimp to do a woman's job or play high or stay home. If you are going to trump after two rounds of a suit, play a moderately high trump, or do not play one at all.
Opening lead against No Trump should be 4th high from your longest and strongest suit.
Length before strength when bidding.
One peek is worth two finesses.