It depends on faith , if you believe ot can affect then, It may affect your reading, However no, it usually don't affect though may spoile your mood of seeing a good cards , but if you're ok woth this then its fine.
*Sleep with them, infuse them with your energy everyday by touching or shuffeling..
*Before starting, a prayer will help
*Try to be very specific while asking question
*You can give a name to your decks, many including me believes they have tgeir own essence thus treat them with care like you would to your friendly pet..
*Meditate and Relax before use
*The less cards you draw the better you go!
*Read the boolet and add additional meaning to each card personally one at a time.
* Cleanse them before new reading and after a reading.
Hope you progress in it.