Passing can be categorical and relative and in your case, I can interpret it as an academic success i.e. you want to score an A in your KCSE examinations in order to have a chance to pursue a dream career. Its everybody's dream to achieve academic success but a few of them get through. Why? I am the one who is going to tell you this 'choose the road less travelled and it will create the difference in the end' the world is crowded with people who think and do things the same way and to join the extraordinary group, you must do things extraordinarily.
According to your question, it's clear to me that your academic goals or aims which is of course a desire to perform well in your exams but every other person thinks the same way and has the same aims the difference is the amount of desire each one of us is ready to apply in order to achieve the desired goals. If then you want to be extraordinary, do the following;
1. Aims and goals are nothing without Objectives
I will explain to you this with an example: Suppose you are a water minister and a million people of your country demonstrate to your offices demanding for water in one dry season. Because they demanded water, you fetch a glass of water and offer them, will they get satisfied? I guess you know the answers, goals without parameters to support them are useless, these people may have either demanded 1000 boreholes or a million cubic litres of water everyday but because the objectives were not stated, the goals were not met.
This is how we fail everyday, we all have goals and aims but we never state our objectives. When you backup your aims with figures, they sound more realistic and achievable. If for example your goal is to pass, then specify the type of pass you want with figures i.e a B+ of 68 points or something like that, being analytical in your approach will help you divide one major task into small divisions that can be worked with easily, effectively and consistently. In success, the numbers are the most important.
2. Are you psychologically prepared
Weakness of attitude becomes weakness of character. Albert Einstein
Anything that the mind of a person can conceive, it can achieve. As humans, we are made of infinite intelligence and if we focus all our activities with a positive mental attitude, we can achieve whatever we want. Passing examinations has more to do with psychology than the curriculum. If you can convince yourself that you are a success academically, nothing can stop you from becoming one. The state of the mind is the engine on which success rides on and it's also where it starts from, this is all about believe, cultivation of faith and delivery.
3. Create your own academic environment suitable for studies
Its logical to design your own academic environment i.e. people around you, psychological setup, the room where you make your studies, your relationship with your peers and people who matter in your life, what you eat, talk and hear and how you react to the same is very fundamental in moulding a way forward in achieving your desired goals. There are subjects well learned when done in a discussion group e.g. sciences and others require private individual study. Learn to differentiate and prioritize your tasks according to their importance. Use scientific methods of study but don't study for examinations, study to absorb knowledge after all it's about delivery and competence that can keep you in your dream job. SQ3R is such a learning method that can assist you make make maximum absorption of an academic content. Use more audiovisual learning tools like videos, radios, charts, academic trips, panoramas etc.
4. What motivates you?
Motivation is either intrinsic or extrinsic motivation. You can derive motivation from within your own [intrinsic] or from external sources [extrinsic]. Before you are motivated by external sources, try to motivate yourself first through evaluating your grades and looking at your potentials and how to nurture them for your progress.
5. Do you have a strategy/plan?
Build a strategy or a plan i.e.
I have read many books on success, successful people's biographies, lives of great people like Albert Einstein, Edison, Graham Bell, Andrew Carnegie, Napoleon Hill, Mahatma Gandhi, Henry Ford, Nelson Mandela the list is long and I can frankly conclude that the secret to success lies in;