its mostly genetics bro....cardio and diet help clean up the look, high reps will help tighten muscles a little more, but this is mostly due to glycogen depletion, heavy weights and cardio allow you to maintain the mass/volume of a muscle for longer whilst getting lean...at least thats how i see it...

high reps for fat burning is myth really,HIT is the best way to milk the calories, ever notice how lean you can stay despiteall the food when you are powerlifting or strength training....