Here we'll talk about pre-flop aspects of cold calling. Firstly, cold-calling is generally bad. You are giving up initiative, often to be in a heads up pot, against a villain who is already showing strength. When you are not in a heads up pot, you end up with poor relative (and often absolute as well) position. So why do we do it?
Recall the three main edges in hold’em: card edge, positional edge, and skill edge. When a villain raises, if we believe ourselves to be ahead of their range cardwise, we generally 3-bet. Thus when we are cold calling, we are mostly trying to push our positional and skill edge. Based on their ranges, we should have a plan for cold calling from the start. The idea is either to potentially bust the player we are involved with by hitting a monster against their made hand, or to take the pot away from them on a later betting round, hopefully with outs to a better hand than theirs if that fails. In general, while these two purposes can merge somewhat, it is best to have a plan for which is the main goal unless it is highly dependent on board texture, meaning that on some board textures you will have fold equity and some you will be likely to stack them. Thus, the two most important questions about our opponents when we are considering cold calling are: do we have implied odds, and two, is their range weak enough that we will likely have fold equity on later streets? The reason the ideas of busting vs. bluffing are separate is that usually you usually don’t have much fold equity if you have large implied odds and vice versa, although there are exceptions.
These ideas can be illustrated nicely by seeing the goals of calling vs. different player types. For instance, vs. a nit who will mainly play big pair hands and AK pre-flop, but will go too far with overpairs and TPTK, we are calling for the massive implied odds they offer. The standard is that we are trying to crack aces with a set. Versus a positionally aware thinking TAG/LAG, we are calling to use our positional advantage to put pressure on them and put them in difficult situations where we can force them to fold better hands or extract value from worse in spots that are easy for us to play but marginal for them due to our positional advantage. Versus these opponents we could either bluff them or bust them based on board texture and betting action and the lines between fold equity and implied odds can become blurred. Versus a maniac we are calling to flop something strong enough to give them rope to hang themselves with. We are calling to bust them, but we may not need as strong a hand to bust them as we need to bust a nit. Finally, versus a passive fish, we are calling so that we can value bet and raise them very aggressively. As you can see then, in all cases the two factors to consider are what are our implied odds vs. this player and what is the likelihood we will have fold equity later on.
Position ties well in with this in that it often tells us more about our implied odds and/or fold equity. For most villains, we can create some kind of range for them based on their position. If they make an EP raise, we can generally assume we have implied odds, while if they make an LP raise, we will often have fold equity on later streets. There are exceptions though. Bad players generally cannot be put on a range based on position, while tricky villains will occasionally mix in more speculative hands EP for balancing their ranges. Also, extremely nitty players will have an extremely strong range regardless of position. We additionally have to consider our own position; more for the risks. For instance, if UTG raises and we call UTG+1, there is a good chance we will play a multiway pot with no initiative and both poor absolute and relative position on post-flop betting rounds. On the other hand, if the CO opens and we flat on the button, we our opening ourselves up to a potential squeeze from aggressive players from the blinds. Further, the position we are calling from and their position also tells an observant opponent something about the strength of our hands. If a thinking UTG raiser opens and we call UTG+1, he will generally put us on either a strong hand or something like a medium pocket pair that can easily make a very strong hand post-flop. Finally, it is generally terrible to cold call from the blinds; mainly due to the disadvantages you have in controlling the pot size being out of position. You lose the implied threat of future bets, and thus much of your fold equity, you often have to pay more if you are on a draw to see if you hit, and you lose much of your implied odds because it is harder to build a pot out of position.
Now we come to what hands to cold call with, and it really mostly relates to whether we have implied odds or fold equity, and also where our implied odds come from. Do our implied odds come from him overplaying strong, but not monster hands? Do they come from him being a calling station, or do they come from him bluffing too much? For instance, versus a nit who overplays big pairs, it might be wise to cold call with pocket pairs only. You will need a very strong hand to beat his, and if you have little fold equity it may be difficult to play draws successfully, so a fit or fold strategy where you attempt to hit a set may be best. Versus a persistent bluffer, we may only need a good top pair hand to bust him, we could add AK/AQ to the list, and if he has poor pre-flop hand selection and will likely play dominated hands we could even add AJ-AT and KQ/KJ to the list. The hand selection ideas versus a bluffer are similar versus a calling station, but in fact hands with huge potential like 33 may be less valuable (though probably still worth playing) versus a calling station, since you will hit a set less often than top pair playing the other range, and a good top pair may be more than sufficient to take his stack. Against all of these except perhaps the aggressive nit whose bet sizing is too small, drawing hands like 67s are pretty weak, since against the group you will likely have no fold equity when you flop a draw, and against stations even if they let you get to your draw, the pot might be too small for you by the time you hit on the turn or river for you to get his stack.
Finally, we should look at our image when deciding when to cold call. For instance, in some cases versus an MP open with us in the CO we may decide that AQo is ahead of his range. However, if we’ve been 3-betting relentlessly it may be time to cold call instead of 3-betting, as 3-betting can open us up to a 4-bet bluff. Similarly, if we haven’t been 3-betting much a 3-bet may be better in some cases than a cold call. Finally, if we are just to active and we pick up a hand like 67s we may just decide to chuck it.
In sum, the most important things to decide in cold calling are whether we will have fold equity or implied odds post flop, and if we do, we may decide to cold call. However, it must be remembered that cold-calling in and of itself is often not good and we must make up for it by a skill and/or positional edge.