When the opponents show a two-suited hand, we have to make a decision as to what would be the best lead?
The rule of thumb is usually a trump lead especially if you are long in their other long suit. No rule is carved in stone. We have to think of the bidding.
1. Did our partner open or did we open the auction?
2. Do we have length in both or one of their suits?
3. Do we have an outside AK to look at the dummy?