My mom insisted I bring pots and pans to college, even though I had no clue how to cook. That led to a friend asking if I would try to make a recipe her french grandmother gave her for her favorite dish.
I carefully read and re-read every line of the recipe and followed it to a T. My friend tried it and her face fell; it tasted like nothing. Later she called her grandmother and asked what I had messed up. "In France, no one needs to be told to add butter or salt."
Newer players want recipes. Bid X with Y. When you have 6 points do this, when you have 7 do that. Unfortunately, recipes that call for points + shape are missing a key ingredient: Suit quality.
What do you need to make a 1-level overcall for instance? Don't say 7-17 points and a 5-card suit. That's at best an incomplete answer. When you have a good suit, you don't need 7 points. When you have a bad suit, you need more like 10 or 11.
Take a look at this hand:
54
KQJ107
432
972.
I would overcall 1
over 1-of-a-minor any day (and at any vulnerability) and you should too. However, if your hand is something like:
Q92
105432
K98
QJ,
Then passing is right, even at favorable vulnerabilty.
For 2-level overcalls, the requirements should be even stricter. You need 6-card suit or a suit that looks like 6-card ( like KQ1098) in order to risk the two-level in addition to a hand that's close to opening strength.
Seat and vulnerability matter, but without an appreciation of suit quality, you'll be making calls that mis-describe your hand.
Preempts are important tools. They can interfere with the opponents, and also describe your whole hand to partner with one call. It kills me to see preempts described as "6-10 points with a five-card suit." The focus of your hand is the suit you show. A suit like: KQ10xxx is begging to be bid. Qxxxxx is not
With none vul, which of these should you preempt in first seat.
A)
AJ10843
98
43
932
B)
976432
AK2
J8
43
C)
QJ9874
43
K92
982
A and C are both good preempts with 5 and 6 points respectively. The suit makes up for the weakness. B is relatively loaded when it comes to high cards, but preempting shows the wrong hand type as you don't want to emphasize a spade suit headed by the 9.
Formulas and recipes often forget the importance of suit quality or reduce it too simplistically (2 of the top 3 or 3 of the top 5). Consider the "Rule of 20" or Rule of 22" which are formulas for figuring out whether you should open based on shape (add your HCP to the number of cards in your long suit and if it's 20 [including two quick tricks], open). Which of these hands should you open the bidding:
A)
B)
A
A2
J8743
J5432
A is a much better hand than B and holding the majors is better than holding the minors.