ATG always has a slight hesitation when first starting it. The tendency (for me, at least) is to want to pull the blade, therefore slicing, in stead of pushing the blade upward. Stretching the skin as much as possible also helps to cut down on the resistance. On my cheeks, I pull down and shave up, but I also pull up and shave up (be careful of the fingers!). I'll do an XTG on the cheeks while pulling down on the skin, and when near my jaw and ear, I'll pull the skin back.
Do be careful of the blade angle. You can raise it, but if you go to high, it will want to slice you.
I hope this helps!
:shave