The best method for installing a new reed into a chanter varies according to the style of reed. Molded or straight cut reeds require a different approach to ridge-cut or shoulder cut reeds. Molded reeds are profiled with a more or less straight taper giving them a much less substantial body of cane above the binding. Ridge-cut reeds have a much thicker, more or less, parallel section of cane above the binding giving them a very thick, strong body of cane with which the very thin tips are supported. Both styles have their own idiosyncrasies and must be treated in a very different way. Both styles will also behave poorly if the wrong technique is applied.
Molded reeds do not respond well to heavy squeezing. A little warm air will usually be sufficient to relax the reed fibers and enable the cane to vibrate efficiently. For an Apps molded reed I recommend that you simply mouth blow the reed for 20-30 seconds. There is enough moisture in your breath to bring the reed to life, it's really as simple as that. It is especially important not to squeeze a reed that has been set to a specific strength prior to shipping as squeezing will completely alter it's strength. Reeds ordered at a specific strength setting it will have been set in the workshop. It would be a shame to go to all the trouble of ordering a reed set specifically to your liking and then altering the setting by squeezing the reed before it is even played in the pipe.
When I set a reed to strength I actually set it to about two inches of water higher than requested. This works because once the reed takes on moisture it will come down by about two inches of water. If the reed is treated with care and a good moisture control system is installed in the pipes the reed should stay at the set strength through most of it's life (Provided you do not suffer from Oversqueezyitis! 1 ).
Ridge-cut reeds require a very different and more energetic approach. They require a more thorough wetting than a molded reed as well as a good squeeze. The way the cane is cut makes it stiffer and more manipulation is necessary to loosen the cane so that it vibrates freely. I recommend dipping your fingers in water then applying that to the tips of the ridge-cut reed. If the reed is the desired strength just hold the blades between your thumb and forefinger to impart some warmth. This will really bring the top hand to life. If the mouth of the reed is too open and the reed is too hard you'll need to give it a good squeeze. Squeeze the reeds from the base, where the binding meets cane, and rock it between your thumb and forefinger. This rocking motion will ease the reed, bring out the timbre of the top hand and allow the reed to free up and become more responsive. This process can be repeated time and time again with ridge-cut reeds.
To get the best out of your reeds you must use the the most appropriate techniques for the reed style. The sound of a reed depends on the cut of the cane. The cut of the cane will determine the techniques used to install it in the pipes. Using the proper technique will ensure you get the best performance and tone from your instrument.
1 See article "Oversqueezyitis" written by Chris Apps for the Piping Times