How do I get good at magic tricks?

You can get good at magic through hours and hours of practice.  Getting a deck of cards and learning how to hold them and do flourishes is a great way to start because magic takes  extreme dexterity that is built through muscle memory in the hands.  This takes hours and hours of repetition to get good at.  Other factors that play into how good you get at magic are your interest in it.  If you are aren't interested in it then you won't get good at magic.  You can also join a club and practice magic tricks with other people that are interested in it too.  One of the best organizations to join is the Society of American Magicians (SAM).