Choose strong verb phrases rather than complete sentences and avoid using the word "I" in your objective. Instead of writing, "I want a job," use the phrase, "seeking employment." Do not ask for anything as part of your career objective; rather, offer your services. When you write, "Seeking employment where I can expand my skills/gain experience/increase exposure," you are essentially asking them to give you something out of the job instead of offering to bring something to their company.