Well I haven't had any problems with tearing with the premade wrappers unless I accidentally poke a fingernail through.
I've gathered some tips along the way. When steaming, either steam on little squares of parchment paper or use cabbage or lettuce leaves that have been sprayed with nonstick cooking spray. NEVER EVER steam directly on the bamboo.
When making potstickers, I always use a nonstick pan and still use plenty of vegetable or canola oil and I don't really move them, just turn the entire pan about half-way through the initial cooking time, maybe jiggle pan a bit, and cook until golden brown on bottom. If there's any resistance when you try to check the bottoms, they are either not brown enough to release yet or you didn't use enough oil. If I remember correctly it takes about 6-8 minutes over medium heat. Then, I rotate the pan back to the original spot, put in the water to steam them, and cook until done, turning the pan again about half-way through to ensure they cook evenly. Total steaming time of about 8-10 minutes, adding water in small amounts if needed so pan doesn't dry out. I've never had one stick or tear doing it this way. You want to pull them when there is still some residual oil/water left in the pan, don't ever cook it totally dry. Just wipe out residual oil/water with paper towels before starting the next batch.