Doing tricks often

Could't find a previous thread about this so yea. FYI i can do some tricks already like flat 3 and 5, cork 7, misty 5. I have a hard time trying the harder tricks often, like i do tons of backflips and 3's but i dont do cork 7's that much. Do most people do this? Is there a way to overcome it other then practicing those tricks? Just something that frustrates me.