How big
That's part of what you need to think of. But more than how big you want to pot to end up you need to ask yourself the pot size trajectory you want to plan on -- how fast do you want the pot to grow?
He gives an example of what I'm talking about although he doesn't get explicit about that part of the plan.
.50/1.00 NL, hero has $100 and villain has $25
Folded to hero on the cutoff whe raises to $3 with JhJd. The villain on the button, an unknown shortstack, calls.
Flop: Td 8d 7c (pot: $7.50)
Our opponent has $22 left in a $7.50 pot. With so little left to bet and so many draws out we are happy to get $22 in the pot.
He suggests betting the pot and getting raised. I'm not so sure I like that plan. It's going to be hard to count on getting raised. In his example trajectory the hero gets all the money in on the flop, which I think is fine.
But what if you bet and don't get raised? There's a lot of cards that might scare you on the turn. Do you really want to triple the size of the pot and leave yourself with an almost pot sized stack left? I don't think you do. I think you want to try real hard to avoid putting yourself into a situation where you have to make a tough decision.
If you check that flop one of two things will happen --
1. He might check, leaving the pot relatively small until you see the turn and decided then what to do. or
2. He might bet, making it fairly easy to just pick up the pot with that little extra right now.
If you check neither possibility leaves you in a real bad spot, the pot is still small enough so if he checks then you can fold the turn if things turn sour. At the same time it gives him a chance to put some more money in the pot now, allowing you to easily get it all in now.
When you think about the pot size you want don't just think about the size, think about how you might get there, and think in terms of multiple possibilities, not just one path.
Give yourself options, and avoid having to make tough decisions later.