A lot of beginners use cards in their deck like Blue Eyes White Dragon, Dark Magician, Gaia the Fierce Knight, etc. and I'm gonna use the Blue Eyes as my first example. Now why put a BlueEyes in your deck I can see why a beginner would because it has 3000 ATK and it is the third strongest card out only surpassed by the Gate Guardian and the Black Skull Dragon but still even if you play it with the Lord of Dragon card your opponet can still kill Lord of Dragon and then activate a trap like Dark Hole, Raigiki, or Mirror Force and destroy your Blue Eyes. There are so many cards in the game that can destroy the Blue Eyes so putting in your deck is just wasting it thats why I wonder why put it in your deck because a Blue Eyes can't last more than 2 turns on the field with all the monster removal cards in the game. I'd also like to say don't put a Dark Magician in your deck instead use Summoned Skull for goodness sake even though the Dark Magician looks cooler to me. The last thing I want to say is DON'T use Gaia the Fierce Knight in your deck its a 7 star monster with 2300 ATK and 2100 DEF the card is just plain sucky. There are some nice tips for all the beginners out there.