Any poker book can give you a fairly simple pre-flop strategy that will be basically correct. On the other end, the river can be solved exactly with a variety of game theory optimal solvers. The beginning and end of the hand are fairly well-defined because there are only so many options.
Pre-flop there is little information available for you to make your decision (for under the gun, there is basically none.) We instead look at the empirical evidence from winning players in on-line databases to get a pretty good idea of the boundaries of winning play in terms of Voluntarily Put in Pot (VPIP) and Pre-Flop Raise (PFR).
Most pre-flop situations, by definition, are fairly common and with so little information we do well to basically play the percentages. Pre-flop play should set us up for positive expected value plays post-flop and staying within these boundaries will help do that.
The flop is where things get complicated because there are 1,755 strategically different flops. Trust me on this, I counted!
Certain types of flops have a bright line around them and are clearly different from the rest. A simple example would be the trip flops. These play different than all others because the vast majority of the time, there are only three poker hands that can be made by the end: trips, full houses and quads (runner-runner straights and flushes are rare but possible).
These flops have a distinct characteristics that sets them apart. The rest of the flops gets murkier. The noted poker authority, Ed Miller, helped to draw regions on the map of all flops. While not strictly defined, he had type 1, 2 and 3 flops.
Type 1 flops have the characteristic that people either hit these flops hard, or not at all. On a flop like K32 rainbow, when you continuation bet and get called, you will often be up against a king. Against a straightforward player this is the kind of flop that you would “one and done” bluff and give up if you cannot beat a king. The flip side of this is that your c-bet will elicit a fold a large percentage of the time.
These boards tend to have a high top card, like and ace or a king. They will often be paired, and have few draws available.
On type 2 flops, there are lots of weak hits. When you c-bet and get called, there is not an obvious answer to the question “what did they call me with?” These boards are often going to elicit calls from gutshot straight draws, a weak pair with backdoor draws, or combo draws with some other feature like a pair or backdoor draw. J83 with a flush draw is a typical Type 2 flop.
When you bet the flop on these boards, you will get a lot more calls, but often a second barrel on the turn will convince these weak fits to fold if they do not improve.
Type 3 flops are highly coordinated, KQT with a suit or 987r. If someone hits these flops, they tend to hit them very hard and legitimately will go to showdown with them. These are flops that lead to boards that tend to be won by straights, flushes, full houses and big two pair hands.
What does this mean at a practical level? Before you continuation bet a flop, you should ask yourself: “What kinds of hands should I c-bet in this situation and why?”
On a type 1 flop of K72 rainbow, the answer might be “I will bet top pair with third kicker or better for value. There are very few bluffs on this board, so I need to dig deep to find some. I will bet any pair nines or worse because they benefit the most from the protection bet.
The counter-intuitive betting of weaker hands rather than stronger hands is because hands like QQ do not benefit from getting JT to fold on K72 rainbow, but 99 does. This protection aspect for the smaller pairs offsets the fact that when I get called I am usually way behind.
If I expect that I might need to double barrel because my opponent will call one street with middle pairs (and not just a king), then I would bluff more often by adding in three-straight plus three-flush hands. These hands can often pick up a barreling card on the turn that allows me to barrel and still win if called up to the turn.”
If you have one of the listed hands, go ahead and bet. If not, check. You are not being a dreaded fit-or-fold player if you decline to c-bet. You have your criteria for betting, your range includes bets and bluffs. You are disciplined if you do this, not a nit. Just make sure your criteria has good bluffs and good value.
What is the plan for the rest of the hand?
On this flop of K72 rainbow, the plan is pretty simple: assume a range for the opponent. For most players, their continuation range is basically just a king, though some of the more adventurous players might call with middling pairs and AQ or AJ. If we have a value hand, keep firing. If we think Villain can have middling pair that will fold, then those three-flush plus three-straight hands will often give us a chance to fire again and get the fold.
These backdoor draws are important because of our mantra:
When I bet, I want to beat the most likely hands to call me, or have a draw that can beat those hands.
These three-flush plus three-straight hands are hands that will more frequently pick up a draw that can win on the river. They will often allow us to bet the turn with high equity when called, even if the opponent has the king instead of the lower pair we were hoping he would fold.
What about a counter-example with a type 3 flop?
We have aces and got called by the button. The flop comes down T96 with a suit. We are often ahead here with our “pair but no ace of flush.” However, this is the kind of board that is going to be miserable for aces out of position. If we bet and get called, the opponent will often have very good equity.
Furthermore we don’t know what kind of draw we are dodging. With a creative player on the button they will be able to pressure us very much on this board.
Imagine for a moment at $2/$5 that the pot is $60 and you have $450 effective. There are four big stacks of red and a couple of green chips. You cut out $60 and push it across the line. Envision this player looking you in the eyes, looking to the flop and then throwing in two green chips and two red chips.
How do you feel about that call? Does it make you wince? It probably should. There is now nearly $200 in the pot and about $400 left in stacks. About 20% of your original stack is in the middle now and your one pair hand could be facing any number of draws or better made hands.
The fact that we do not like getting called at all on this flop indicates that aces are not the kind of hand we want to lead out with for value. They almost feel like a bluff that got called. If aces feel like a bluff, could we instead find other hands that would have more equity when called?
Following our mantra, we would probably be betting only the stronger hands like two pair plus for value. We would be choosing to bluff with good flush draws, good straight draws and combo draws that we might have with features like a pair. Those kinds of bluffs have serious equity when called so we feel a lot better when called. We might even consider checking a lot here but having a wicked check-raise range. That is a topic for a different time.