Kata is something that must be learnt from a qualified and knowledgeable teacher. Although books and videos can enhance understanding and aid memory, they are no substitute for proper instruction. Your instructor will be the most important person to help you with regards to your karate.
The important thing is how good the instructor can make you, as opposed to how good they are. You require a Sensei, not a bodyguard. Visit a number of dojos and look at the standard of the students, the way they are dressed and their attitudes to one another as well as to the instructor. The Sensei / Student relationship is a special one. If you find a Sensei with a deep understanding of karate and a genuine love of the art, and if you are prepared to study hard with dedication, openness and honesty, then you are sure to make good progress in all aspects of karate.
How you are taught the kata will be a matter for your teacher. It is common for the kata to be taught in stages. For example, the first few moves will be taught, and then when the student has a reasonable grasp of them, they will be shown the next couple, and so on until the whole sequence is remembered. The techniques will then be further refined as the emphasis shifts to timing, rhythm, correct use of strength etc. As the student progresses, the corrections will become more and more finite as they strive for the unattainable goal of perfection. Once the kata is of a satisfactory standard, the student could begin to receive instruction on the applications of the movements. Understanding the applications will improve the student’s performance of the kata. As the student’s performance of the kata improves so will their ability to apply the techniques. This spiraling effect should be at the heart of kata practice. When your Sensei is happy with your kata then and only then will he look at putting you forward for your next grading. It is far better to have a good understating of one kata than a superficial understanding of many. Do not rush when learning the kata or be in a hurry to move on to the next one. Take your time and always emphasize quality over quantity.
One of the accusations commonly directed at kata practice is that it is ‘boring’. Part of the problem is that few people understand kata and as a result the students fail to see any value in its practice. Another problem is the constant repetition that is required for competence to be achieved. I am sure that the world’s best sprinters have at some point in their career got bored running up and down the track. Top golfers probably get bored practising their putting and Olympic weight lifters get bored of lifting weights. Yet these people possess the necessary mental strength to continue to practice. Long after others became ‘bored’ and stopped practising, they can be found still working and that is why they are at the top of their field. Everyone wants to be good and yet only a few are prepared to put in the work that is required to achieve high skill levels. Get a good teacher, gain a good understanding of the kata, take on board any criticisms and practice relentlessly if you want your kata, and indeed all aspects of your karate, to be of a high standard.