You wont get the quality as good as most of the other gopro video on youtube with a Hero 2. They were probably shot with Hero 3, 3+ or Hero 4 and there is a huge difference in image quality between the hero 2 and 3. You can try doing some color grading to get your images to pop a little more and add a little contrast.
GoPro does a lot of grading and post work on all of their videos to make them looks a lot better.