In previous articles I wrote that a standard open-raise size for cash games is 3bb (+1bb per limper). The 3bb standard is what we recommend complete beginners stick to in the Bankroll Builder forum. However, there is some scope for altering the size according to table conditions. 3bb is fine if everyone is a TAG regular sitting on 100bb (and sticking with standard sizes is recommended at higher stakes, in order to disguise the strength of your hand), but on 2NL tables, you'll find a variety of player types stretching from crazy maniacs and calling stations that play any two, to ubernits that sit around waiting for QQ+. Stack sizes can also vary from 250bb ($5) or more right down to guys continuing to play with 23c or something stupid like that. A particularly common stack size at 2NL is 80c, as another forum recommends newbies buy-in for this minimum amount. If there are more than two of these mid-stackers at my table, I'll often leave, unless it's clear that they are particularly bad short-stackers who don't have the patience to stick with the tight-aggressive medium-stack strategy (MSS) they should be adopting . (I want to play against loose players with big stacks, not tight players with short stacks).
In my experience, most 2NL villains aren't particularly observant of bet-sizing tells, as they seem more concerned with their own cards. We can exploit this leak by betting smaller when we don't have a strong hand and we don't expect to get called, and we can make larger bets when we have big hands and we do expect to get called. Adding or subtracting a blind or two here and there might not seem like much, but these blinds add up over time and can improve your bottom line.

One such scenario for selecting a smaller than usual raise size occurs when you're on the button with a weak hand (e.g. 65s or even ATC) and the players in the blinds are very nitty and/or short-stacked. I'll often go with a 2.5bb size (5c) in this situation, so that I'm getting a cheap price on my steals. If the shorty/nit plays back at me, he obviously has me beat, so I fold and lose the minimum. Often these shorties/nits have already hit the “check-fold”  button by the time the action reaches me, so they don't even pause to see the bargain price I'm charging them to see a flop. In nitty Zoom games, even a minraise (4c) on the button can win the blinds, so give that a try.
It might seem that the smaller raise size would mean your steals get called more often, but you saw how often I was successful with my steals in the previous article. For the majority of the 100k hands I played, my default size for opening on the button (and sometimes in the CO too) was 2.5bb. Despite the tempting pot odds I was offering the big blind (2.67 to 1), he'd still fold about half the time. A smaller open also means the stack to pot ratio remains high. Many of the specualtive hands you will be raising in late position benefit from higher SPRs.
If you have a hand that's closer to the top of your range in this situation, stick with the 3bb standard, in order to start building a pot you intend to win post-flop.

At the other extreme are the times we have a strong hand and we expect to get called. Typically this is because there is a loose player that has either already limped in, or he's to your left and is yet to act. Loose players seem particularly keen to “defend” their blinds, and they will often call with all kinds of junk in those seats because they are getting a discount. We can exploit their loose calls by making oversized opens with our monster hands. If I identify a fish in the blinds, and I have QQ+ in early/middle position, I will use a size of 4bb or even 5bb (10c). This size will usually disincline multiple callers (observant regs will recognise we have a monster) and get us heads up agains the loose caller. Since he will generally have a weak hand to start with, he'll usually have a weak hand on the flop. It will be hard to get three streets of value if villain is super weak. We therefore get most of our value pre-flop.
e.g. I open for 10c UTG with . It's folded to the loose-passive fish in the small blind, who calls with . The big blind folds, so there is 22c in the pot on the flop. I make a c-bet and (most of the time) villain folds. I make 12c profit, and all the value came pre-flop.
If I'd just opened for 3bb (6c), then my profit would only be 8c. The larger open-raise led to 2bb of extra profit and the hand didn't even go beyond the flop! If there was a call on the flop, then the pot will be even bigger on the turn and river, and we should be able to get a whole stack in by going pot-pot-shove.
The plan works in a similar way when you are isolating a limper, and in these cases it's especially useful to know if the player plays fit-or-fold post-flop. If the villain limp-calls often, but folds to c-bets more than 50% of the time, you can isolate him pre-flop with an oversized raise (expecting him to call) and then c-bet 100% of flops in position, expecting him to fold. Players who “limp-call pre, check-fold post” are basically dropping their loose change on the table. It is your job to pick it up, so get busy with isolating them!

You may have heard of Nathan 'Blackrain79' Williams; the biggest lifetime winner at full ring 2NL. He's played over 2 million hands and won thousands of dollars with an extremely high winrate. Overbets (both pre-flop and post-flop) are a big reason for his success. In his e-book, he says that against particularly loose villains, he'll make outlandish pre-flop raises with his big pairs and AK. I tended to avoid Blackrain79 when I saw him on the tables, but I came across several players using his strategy. There was one guy in particular who I had a perfect read on. No matter what his position or the prior action, he would always open for 26c with AA, 24c with KK and 22c with QQ. It initially struck me as very odd that he'd open for 13bb with AA, because I would never call a bet of that size, so I thought he was missing value. But the thing is, plenty of players did call the overbets. This particular villain was actually a terrible player, running at something like 38/6 and spewing all over the place post-flop, but just because of his oversized opens with his monster hands, he was making a long term profit.
I'm not going to recommend that my readers go out there and start opening to 10bb with a big pair, but bumping up your sizing a bit when you have a specific reason to do so should increase your winrate.

Over-betting post-flop can also be tried (it works very well for PSO member Sandtrap!) but that topic is beyond the scope of this article. I'll include some hand replays of my own overbets and value-shoves when I get to the post-flop section of this series.

In the meantime, if you spot players making non-standard open-raise sizes, be sure to take notes of what the sizes represent. It's extremely useful with regard to hand-reading if you know, for instance, that a particular villain uses 5bb when he has JJ (he wants you to fold), but only minraises when he has AA (because he wants action), in the same way it's easy to put a maniac on aces if he's been min-raising 60% of hands, and then suddenly limps UTG.

My next article will probably be concerned with ranges for calling/re-raising when we are facing a pre-flop raise. Till then, good luck at the tables!

Questions, comments and suggestions are welcome as usual, but note that I'm more likely to respond in my blog thread on the forum.