For what it's worth - my technique, used to load God knows how many thousand sheet films:
I tend to pull the sheath almost all the way out, inspect each side of the holder to check for dust, and remove this with a flat brush if necessary. My biggest problem then follows - forty years of bad guitar playing have left me with callouses on the ends of my fingers which mean I have to be extra careful to pick up only one sheet of film at a time, and without an interleaf paper. With practise, I find I can pick up film by the edges only between the thumb and middle finger of my left hand. I then grip the film using the thumb and index finger of my right hand at the top right hand corner where the notch is to indicate the emulsion side.
This is of course fairly standard technique - what I do find valuable is to place the thumb and middle finger of my left hand on the end of the film rails. This means I can locate the leading edge of the sheet film first time with no fumbles. As soon as the film is located in the rails, I move my left hand around and use the middle finger to hold open the hinged flap at the end of the film holder so that the film does not scrape against this as it is pushed home. The old-style MPP film holders are particularly critical in this respect - the end flaps have a cast dimple at their center underneath - if you let this touch the film, you get a scratch the size of the Grand Canyon!