Tips on building a good deck

Your deck isn't perfect unless you know your combos and can sustain a winning streak of at least 4-5 duels
Don't destroy a deck just because it isn't winning you duels, just modify it until you feel that it has been perfected
And finally, try to have decks that have different strategies that way you can possibly counter an opponents deck when you get into bad situations to quickly reverse the situation into one in your favor

you might want to repost this in the deck area of the academy, itd be more helpful there