Your vision, mission and goal should define who you are and what you see yourself achieving in life.
Your vision should refer to the big picture view you have of yourself as a person. For example, my vision of myself might be a vision of a strong, independent, successful, contributing member of society. Think about main, descriptive phrases and ideas you want to come to other's minds when thinking of you. This is your vision.
Your mission refers to what your wish to accomplish in life. Often this refers to a career but not always. Think about what you view as your calling in life. How do you contribute to the world? For example, my mission in life is to educate and facilitate learning in my personal and professional life each day. Think about the ways that you make the world a better place. This is your mission.
Consider the steps that you need to take to carry out your mission. These steps make up your goal or goals in life. The successfully achieved goal allows you to succeed in your mission and become the person your describe in your vision. For example, my current goals include finishing a second masters degree and publishing amother teacher resource book. Your goals will change as you move toward achieving your mission. Keep creating new goals that maintain your vision of yourself.
This is a question that only you can answer. It depends on a few important variables. Let me get you started, so that you can think through the various issues that you will need to think about.
First, you need to ask for what field, event, or area that you are creating a vision, mission, or goal. Knowing this will allow you make more intelligent and specific goals. For example, if you are taking about school, then your goal can be to get an A in history. The more specific your goal is, the better.
Second, you should assess yourself and your past performance. Knowing yourself is also an important step. I should also say that this is not an easy step. Self-knowledge is difficult and requires maturity. As you evaluate yourself, your goals have the benefit of being realistic. I find that small and incremental goals add up in the long run.