Your goals must be specific. One might say, "I want to be successful." Well, who doesn't? But can you define what success means to you? Success to one person may mean becoming CEO of a company, while to another person it can mean getting home from work by 6 o'clock every night.
You must be able to measure the outcome of your goals. When you set a goal you must include a time frame for achieving it. You can also specify amounts. For example one can say "in three years I want to be halfway through graduate school."
Don't be negative. Make sure your goal is something you want rather than something you want to avoid. For instance your goal shouldn't be "I don't want to be stuck in this job for another four years." Instead your goal might be "I want to improve my skills over the next four years so that I qualify for a better job."
Keep your goals realistic. Make sure you have the ability and skills necessary to reach your goal. My goal shouldn't be "I want to win a Grammy Award next year" if I don't have a recording contract, haven't made a record, and can't even carry a tune. If you're still intent on that goal, make sure your short term goals include acquiring some of the skills you need.