If you have trouble doing a Faro shuffle with a new deck, flip it over and try again. The edges of cards are slightly angled due to how they are cut from the sheet, and with most decks the angle is more favorable if they are face up when brand new. After a bit the edges get rounded which is why it's easier to do the Faro in both directions.
When I open a deck I Faro it 8 times, because I like that it goes back to New Deck Order when you do that. It also gives me a decent idea of how the deck is going to be handling. That's less of a concern these days when all the custom decks are more or less the same level of quality, but back when I started there was a pretty wide range. Then I just handle it - bend it one way then the other, start practicing sleights.
I also recommend working with decks in various states of 'broken in'. I used to keep decks all around the house, anywhere from brand new to should-be-thrown-away broken in. The reasoning being that if I ever did borrow a deck to perform I wanted to be able to use that deck, regardless of whether it was a nice new one, or the deck that's been in the junk drawer for 10 years.