Believe it or not, how the cards were cut at the printer (face up versus face down) affect how they faro. If you have a deck that seems to bind when you try to faro them, try turning the cards over. They should slip in more easily.
Also, the faro is not a heavy handed move. It takes a light touch.
It also helps if you use your pinky to act as a shelf that the two corners of the deck can rest on.
In other words, the left hand is holding its packet, palm up from below.Your first finger is on the short side of the deck off to your left. Its pinky is at the corner nearest the audience, on the short side that's on the right. The right hand is holding its packet, palm down, from above. The thumb is on the long side near rightmost corner. The first finger is curled on top. The other fingers are on the long side nearest the audience. (In truth, my pinky curls around a bit and is actually on the short side to my right.)
Move the packets toward each other. You want the two corners that are nearest the audience to butt up against your left pinky. Your left pinky is like a post sticking up between the two halves.
Now, with the packets stabilized, pivot the packets inward. The two corners should come together. The packets should not be perfectly parallel, but angled upward slightly. In other words, the two packets should make a small hump, not a valley.
Now allow the bottom two cards to begin to weave. If they bind up at this stage, turn the deck over and try again. Once you get the first few cards in place, then simply move your right hand slightly away from you. Do not increase the pressure, keep it steady. (In truth, you can move either packet in either direction but you do NOT want to "saw" the deck.)
The deck will practically weave itself.
For a great write up of the Faro, see The Complete works of Derek Dingle by Richard Kaufman.