1. She offers an objective point of view. Most job seekers get overwhelmed with all their information and have trouble choosing what to put on the resume and what to leave off. A second person (whether that's a professional resume writer or your friend doing it for free) can objectively sift through your information and select only what's relevant to your job objective.
2. A professional resume writer will get your resume done! If you've been procrastinating about your resume (the way most of us put off doing our tax returns) then you need to put it in the hands of someone who will get it done in a timely manner.
3. An experienced resume writer has insight. She will likely have written resumes for other people in your industry, including managers who hire people with your job objective. That insight into the hiring manager's mindset can pay off when she writes your resume.
Here's how to select a professional resume writing service:
1. Speak directly to the writer with whom you'll be working -- not just a sales person, but the actual person who will be constructing your resume. While asking questions about your situation and the logistics of the writing process, get a sense of the chemistry between you and she. This is an important aspect of the success of your resume. You want someone who is a good listener, and asks probing questions that draw good responses from you.
2. Find a writer who works collaboratively with her clients. If possible, meet with the writer in person and sit with her at the computer while she develops your resume. If you're an integral part of your resume's creation, you'll end up with a resume that represents you effectively in the job market. This should take about three hours -- time well spent because you'll leave with a completed resume, and you'll understand the strategy behind it so you can tweak it yourself if you need to. By the way, if you can't meet with the writer in person, try to simulate this process by phone and email.
3. Price should be determined by the hour, not by the page. You're paying for the writer's expertise, not simply her typing. For example, it sometimes takes longer to write a concise one-page resume than a rambling three-pager because of the editing time.
If you can write your resume on your own, that's great. But if you find yourself putting it off, or not getting results from the resume you've written, then by all means, look into hiring a professional resume writer to get the job done.
This post was written in response to the LinkedIn question: Are there any recommendations or thoughts regarding professional resume writers?, to which there were several other answers.