Tip 6: "Use that negative double!"
South has a text-book negative double over 1 but failed to make it. If North knows that South is not broke, North will venture 3 for a much better score, even if 1-down.
This South failed to make a negative double over the ghestem 2 bid that would promise 4+ hearts, as East showed s + s. South had another chance to act over 2, being in the balancing seat. Furthermore, due to a misdefence, opponents made +1 for a 92% score. Ouch.
South exonerated herself after failing to make a negative double over the ghestem bid, but her 2 balancing bid pushed East to 3 and with exact defense this went -1 for a 70% score to N/S.
My tip to you: The negative double is one of the most valuable tools in bridge for improving your scores. Use it often!
Remember that after 1 or 1 opening and a 1 overcall, a double guarantees 4 or more hearts;
and after 1 or 1 opening and a 1 overcall, a double shows precisely 4 spades, and a 1 bid will show 5 or more. Useful tip!