Critically evaluate yourself. Look for what needs improvement and seek ways to improve it. However, remember that you are your own worst critic—you are usually doing much better than you think. Do not expect overnight success. If it were easy, everyone could do. Progress in Taekwondo is not always level and consistent. Some days you do well, some days you do not do so well. Progress comes in small increments until one day it all "comes together" and you feel like a true martial artist.
Learn the Basics
Sometimes fundamentals are overlooked in the haste to become a black belt. Perfection of the basics will help you more than training for high kicks. The discipline you gain from the process of perfecting the basics during training will be more useful to you than the techniques you learn from the training.
Individual students learn in different ways. You must find which way works for you. Once you know which type of learning works best for you, you may adjust your training to accommodate your individual learning needs. For example, you may need to see a technique performed repeatedly before it makes any sense or you may need to see the technique in the context it is used. You may need to have the instructor facing away from you so you can align your body accordingly and mimic the instructor's motion. You may learn a hyung/form/pattern easier from a book or video at home at you own pace rather than in class. These are just some of the numerous ways a person learns. If you do not take the time to discover how you learn, you will have a difficult time learning as the techniques get more complicated.
Sometimes we learn without even knowing it. Many times parents bring their children to Taekwondo class, and stay and watch the class each time. After a few weeks or months, the parents decide to start training themselves. At their first class, they perform so well that people ask them if they have trained in the martial arts before. The parents find that they have absorbed a lot of information just from watching classes.