When writing a career objective, think about the employer's needs rather than your own. If you need help getting started, look at the job posting, and pull out keywords and phrases that you can include in your objective.
For example, if the employer is searching for an "ambitious graphic designer who can provide clients with outstanding print and web graphics," use that in your objective like so:
Looking for a challenging position as a graphic designer where I can use my print and web design skills to exceed client expectations.