If, as leader, your long suit is worthless, and your hand is
generally weak, there is a chance that your short suit may prove
to be your partner’s long one, and that the lead may help him to
establish his suit. While the odds are two to one against the success
of a short lead, in this case it may gain and certainly cannot lose
much. If, however, you hold five or six cards in your suit, open it;
there is always a chance that your partner may hold sufficient length
in the same suit to help you establish and bring it in.
If your long suit contains but four cards headed by one honour, king,
queen, or jack, with no other re-entry card in the hand, and you hold
a good supporting short lead, like jack ten or nine (particularly if
the make has been passed, and your short suit is a red one) the short
opening admits of no criticism.
If you hold a three or four card suit headed by ace, king, and queen,
no matter the length in other suits, the opening lead should be from
the ace king queen combination. With three cards of re-entry you can
certainly afford to lead one of them to determine whether conditions
justify the long suit lead.
The dummy hand may discourage the lead of your long suit and make it
advisable to try for your partner’s suit instead.