Question

How can I make this sentence better for my objective on my resume.

To obtain an administrative assistant position where my professional skills will be used to the fullest.

Answer 1

Do you HAVE to have an objective statement? Usually those are pretty lame and unnecessary.
http://owl.english.purdue.edu/owl/section/6/23/
Check out Purdue University's section on professional writing, including resumes and cover letters.

If you absolutely have to include this unnecessary item because of a class assignment, start out like this:

To work as an administrative assistant ...

What are those "professional skills"? Exactly what do you mean?

What does "the fullest" mean? It's a very awkward phrasing and is just about meaningless.

You'd be far better off to include a section called <b>Core strengths</b> or simply <b>Strengths</b> in place of Objective -- and then bullet-list those strengths in detail. Here's an example:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Occupational Expertise

Interaction with customers, in person and via telephone
Communication with staff
Computer use:
~ Basic Word and Excel
~ Data entry
~ Internet: email, searching, web-publishing

Operations management
Problem solving and conflict resolution
Ordering and inventory
Budgets and cost controls
Profit and loss statements
Staffing
Payroll