Opening Leads. They're the card that sets the tempo of all bridge hands, and it is the first strike that the defense gets. Sometimes declarer's contract is rock solid and the lead doesn't matter, or sometimes the contract is too high and declarer is destined to fail.
Do NOT blind follow the so-called "rules", but rather listen to the bidding and try figuring out what Declarer's plan will be and how to counter that plan. Are you ready?