In the semi finals of the Spingold, which is world class standard, both South players got this wrong.
Let the opponents play when they are misfitting, don't compete!
Both south's thought: I am not vulnerable, I have both of the other suits, this should be fine.
However, it is a very big mistake to bid - the bidding suggests that the opponents are in a misfit. In 2♠ the opponents are in a 7 card fit. The decision to compete put NS into a 7 card fit of their own, on the 3 level. This was doubled for -500.
when the opponents are in a fit, it is good time to compete. When the opponents are not in a fit, it is best to just defend.
The most important signals
Double or bid?
Bid as high as possible!
Defending against a multi 2♦
Transfer or not?
Nv compete
How strong vulnerable?
Preempt suit quality
6322 and 7222
2♣ opening
Doubleton lead
Passive lead
When to lead active
1N with 5422
Takeout double
Negative double
Splinters
Competing partscore
Try not double
Ace Ace King
2 level overcall
Lead Trumps #1
Lead Trumps #2
7 card GOOD suit
To open or not, pre-empt or not
Let the opponents play when they are misfitting
The strongest hand
Be practical
Losing trick count bidding
Favourable vulnerability
Be a nuisance
Big trump fits
What does 3♥ show?
Mental game
6+ card suits
Use puppet stayman more
Don't push slam in competition
The unusual 2♠ bid
Intermediate jumps
Conventions
Choice of equal cards
Don't false card
Never preempt with 11 points
Is the bid forcing?
Double, Double
Double 1NT, next double
Counting Habit #1
Opener rebidding bad suits
Responder bidding bad suits
2♦ opening
Don't split honors