The accordion, because of its vertical keyboard, requires correct placement for maximum technical capability.  When in seated position the bottom section of the keyboard SHOULD NOT BE INSIDE THE RIGHT LEG.  This blocks the bottom section of the keyboard at an inward angle thus forcing the hand position to be twisted at a severe technical disadvantage.  The keyboard should be parallel with the center line of the body.  This will allow a proper angle for the hand position.  To accomplish this, the straps should be tightly adjusted, preventing the accordion from moving side to side upon reversal of the bellows direction.  When the keyboard is correctly aligned, the technical aspects of fingering, such as the crossing of the 4th finger over the thumb from C to Bb, can be executed with confidence and accuracy.  The photo on a Charles Magnante arrangement provides the best visual example of correct keyboard placement: the keyboard is only a few inches below the chin, black keys directly in line under the chin and vertical with the center line of the body.  This positioning is ideal for both standing or sitting and will present a professional confident appearance and performance.

Rebuttal from Joe Natoli (posted 9/24/02)
As you know, the opinions of the articles do not necessarily represent the opinions of JANPress Publications and on occasion, JANPress reserves the right for rebuttal (or more appropriately "alternative suggestions"). 

In my personal experience, I have found Gary Dahl's suggestions above to be true and helpful some of the time during performance. However, like anything in life, it is not always recommended to conform to rigid rules in all situations. It is very important as a performer to be adaptable to the requirements of the performance situation. Such is the case with the recommendation above that "bottom section of the keyboard SHOULD NOT BE INSIDE THE RIGHT LEG." In my experience, there are many times when having the keyboard on the inside of the right leg can create more control, especially when performing bellows shakes (a.k.a. tremolos), or when a particularly difficult passage requires increased inward control of the bellows and the performer is not playing at the highest registers (where the leg could interfere with proper hand position). 

But I am also not so naive to think that certain performers may benefit from using Mr. Dahl's recommendations continually. Certainly, everyone is different and everyone can illicit art from their instrument on a very personal level, sometimes in the most unconventional ways. Witness for example the very, very unorthodox puffed out cheeks of the trumpet jazz great, the late Dizzy Gillespe. Most trumpet players could never perform well using the same techniques, yet what wonderful jazz Dizzy produced with those balloon cheeks! The same goes for accordion playing and bellows technique. There are foundational guidelines that assist a player in producing elegant sounding music, but beyond that, it always still comes down to individual preferences, and rigid rules will not always work for everyone.  Just my opinion. :-) Thanks for listening.