The previous article spoke specifically about betaori's timing, the next two articles will go into detailed explanations about the important points of betaori and techniques.
Again, betaori is totally giving up your chances of winning, reducing your chances of dealing in to the lowest. Hence at this stage, especially those who are new to betaori, don't be afraid to dismantle good mentsu or taatsu, or attempt to reach tenpai or even try to win.
The text below will start to explain the related points.
1) Betaori starts with the safest tile
If the reader paid attention to the previous articles, then you should know that this is not the first time I've said this. As this is an important principle in betaori, I'll patiently repeat it once more.
[First image in http://blog.jpmahjong.net/read.php/544.htm]
Shimocha declares riichi, it's obvious that this situation requires betaori. A hand in suushanten, if it's because [I am the dealer] and recklessly try to attack, you'll only lose even more badly.
When you're in betaori, you better prepare to sort out the safe tiles in your hand in order.
Which are the safest tiles now?
The safest tile is of course ton, the genbutsu of shimocha. As haku is already pon by toimen, therefore it's a 100% safe tile. At the same time, don't forget that 7 pin was pon by shimocha, therefore it's also a genbutsu.
What's the fourth safest after that? A lot of people think that it's suji of 9 wan... The correct answer is 9 pin. Toimen pon the 7 pin, and the last 7 pin is in your hand, in other words, 9 pin is a no chance tile. There is also two other 9 pin discarded, 9 pin can only be a tanki wait, it is the fourth safest tile. 9 wan is a suji-pai, but there are no other 9 wan discarded, therefore it's degree of safety is lower.
Therefore the betaori discard order in this situation is: Ton/haku -> 7 pin -> 9 pin -> 9 wan -> 9 wan
The most common mistake by beginners, is over reliance on suji-pai, discarding 9 wan thinking that it's relatively safe. This is a bad habit, because it is not rare to deal in over careless mistakes. The thing to note is, after discarding genbutsu for 2 turns, more genbutsu could appear, and you may not even need to discard 9 wan. Don't underestimate such triviality. During a few hundred games you play, there could be a few hundred hands you need to go into betaori for, and a stricter betaori could cause you to deal in a few hands lesser.
2) Try to hold on to safe tiles common to multiple players
On the other hand, once your hand holds several genbutsu, and you decide to go into betaori, I will first discard genbutsu of number tiles. The reason is that if another player starts to attack later, then your word tiles could be used to defend against both players. The danger about holding genbutsu of number tiles is, once another player declares riichi, this safe tiles will turn into dangerous tiles.
[Second image in http://blog.jpmahjong.net/read.php/544.htm]
The situation is currently in betaori. The 8 pin discarded by kamicha is a new genbutsu. You should discard 8 pin here, and keep the xia, which is relatively safe to the other players. In the real game, toimen discarded 3 sou and declared purse riichi. This xia became an important safe tile.
Let's cite another difficult example.
[Third image in http://blog.jpmahjong.net/read.php/544.htm]
Shimocha is in riichi, you need to go into betaori here too. Although 8 wan and 9 pin are both genbutsu, but you should discard 8 wan here. The reason is that toimen discarded 6 pin, 9 pin is a relatively safe suji-pai. If toimen declares pursue riichi afterwards, you still have a safe tile to discard.
There are people who assume that there is no difference between 8 wan and 9 pin, this is a casual thought. Betaori is not just discarding the genbutsu of the player who declared riichi. A person who is excellent in betaori, will take careful note of the order he discards his tiles. Remember, your enemy is not only the one who declared riichi.