I float the bag unopened for a bit to let temperatures match, then add some tank water to the bag and wait a bit, then add a bit more water and wait some more, then (unless the fish is belly-up) stick my hand in the bag, scoop out the fish and plop him in.
I also don't like the idea of putting store water in my tank.
Float the bag to make sure that temperature and pH matches. If the pH is off, then start drip system going (might have to empty some of the water a few times). Once the pH and temperature matches, fish are then placed into the quarantine tank, without any of the water from the store.
Once the fish clears quarantine, they're added to the main tank.
Never add water from the LFS to your tank water, never know what may be lurking in there. I float the bag unopened for the first fifteen minutes, then I open the bag & add water from my tank to the bag in 10 to 15 minute intervals starting out with very little than increasing the amount of water each time. I do this for 1-1 1/2 hours.
I float the bag and add water as everyone else does. Thing I do differently is after I finish adding aquarium water to the bag I take the bag out, and pour the water (and the fish) into a bucket through a fish net. I then take the netted fish and put them in the aquarium.
I do like Momotaro, but mine go into a QT tank, never into my comunity tanks. Never had a problem doing it this way. I would hate to set lose a diseased lfs fish into my tanks and I don't want to add lfs water to even my QT tank.