A valuable method for setting up extra tricks is to use a long suit, but it is very important to have an entry to run this suit. With this in mind, it can be wise to
If partner makes an opening lead and you are not trying to win the first trick, you usually want to indicate whether you would like partner to lead the suit again.
How do you decide whether or not to open the bidding? High card points? Distribution? Honour tricks (if you are old fashioned)? In truth, it's probably a