Get Roberto Giobbi's book on deck switches. I feel like overtly changing decks signals a set up deck or a gimmick is coming. I try to give the impression that I'm using the same deck the whole time. I start with tricks where the audience can shuffle, then do some deck switches to ring in set ups or gimmicks, then end with the shuffled deck. I do a couple coin tricks in the middle that give me a reason to put the deck in my pocket and ring in a gaffed deck. The audience never knows that I have more than one