Fuente: September 2014 ACBL Bridge Bulletin 
This is a new series looking at bidding problems, that can be awkward. I will show your hand and partner’s hand and propose an auction. For the most part, 2/1 will be used. Occasionally, I will discuss how a less structured method might handle the hands.
South opens 1 and the opponents remain silent. Using a 2/1 system, how would you bid these hands? Here is my suggestion.
Comments:
1 by South: Routine.
1NT by North: When you respond in a suit at the two level playing 2/1, you guarantee game values. One style of 2/1 also promises a useful suit. You might do this with four cards, but five is preferred.
Note that you must not respond 2 with only a four-card suit. There is no need to bid 2 because opener will almost always bid hearts next if he has four of them. When you have at least three-card trump support, here are two rules you should use:
• With three trumps and limit- or game-forcing values, do not raise the trump suit immediately. Find another auction that will let partner know you have only three trumps.
• When you have four or more trumps and limit- or game-forcing values, make whatever bid you have to show your trump support. Do not bid new suits first. Raising right away puts partner’s mind at ease about the trump fit.
On this hand, North does not have four-card trump support or a real suit to bid at the two level. So North first bids 1NT, forcing. North can support spades at his second turn.
2 by South: Pretty obvious. This bid promises only three clubs in 2/1. In addition to denying four hearts or six spades, it promises that clubs are at least as long as diamonds. Further, although 2 is a wide-ranging bid, it denies a really big hand.
4 by North: This bid shows three trumps and game values. North denied a good suit when he did not make a 2/1 response. His usual hand is a balanced 12-14 points with no slam interest.
Pass by South: With a minimum, albeit shapely, hand, South is content to play 4. Mostly sequences like this are adequate, but sometimes 3NT will be a better contract.
Using standard methods where 2/1 is not forcing to game and where a 1NT response is not forcing, what auction should you use?
1 by South: Still routine.
2 by North: If you have no waiting bid such as a forcing 1NT response, you are obliged to respond 2. This is ugly, but it is better than making a strong raise of spades with just three trumps.
3 by South: South is happy to raise clubs with four-card support and a singleton heart.
4 by North: This should show game values with no slam interest. You should be in agreement that 3 is forcing, which means that responder does not have to jump when he has a hand with slam aspirations.
Pass by South: South knows that North could have bid something other than 4 if North had slam interest. South has a nice but minimum hand.