When you set goals, write them down and make sure they are meaningful to you. Here's one SMART way to set goals...

SMART is short for:
Specific, Measurable, Achievable, Realistic, and Time bound.

Let's take a look at the goal, "I want to do well in school," and turn it into a SMART goal.

I want to get a B on my mid-term exam. To do this, I will read as much of the assigned material as I possibly can. Then two weeks before the exam, I will study the course material for one hour, three times a week.

Here is what makes this a SMART goal:
Specific: You're focusing on a specific exam: your mid-term exam.
Measurable: You will measure your success by the grade you get (a "B") and by how long you study to get it (one hour three, times a week).

Achievable: You've achieved a "B" on a test before. Or you know that if you apply yourself, you can achieve a "B."
Realistic: You work 25 hours a week and know you can't possibly read all the assigned work. But, by focusing on the important parts of the assigned work, you know that achieving a "B" is realistic.
Time bound: You've set a date by which you will accomplish your goal: the date of the exam.