With the auto threader apply even pressure and don't push it down too fast and make sure your pressure foot is up or it won't thread. Also make sure you have the thread going in the right direction (follow the arrows on the auto threader) or it won't thread either.
Solvy: Gently pull as much of the solvy off as possible without tugging on the stitches. I keep a spray bottle full of water and squirt water on it which makes it dissolve. you can gently blot with a soft towel after wetting it to expedite the removal. If you have time you can put the garment in the washer on the rinse cycle and that will remove the solvy (if you do this you don't even have to pull any of the solvy off). I usually don't have that much time. I'm usually spraying with water and then using the blow dryer to expedite drying so that I can get it shipped out
One more thing the solvy will remind you of plastic wrap.
Cut Away: Once you are finished trim the cut away down to where there is a small margin around the design being careful not to cut the shirt or your stitiches. I have a pair of applique scissors that I use for this. One of the blades is flat and fat and the other is just typical scissor blade. The flat blade is what goes next to the shirt when cutting the stabilizer. This helps you not to cut the shirt.