To distinguish the good resume writing services from the bad ones you need to find out how they proceed with the task. A good service asks you to fill out an online question. They also set you up for an interview with the writer. This ensures that the writer is aware of all details that must be present in your resume. If a personal interview is not possible they may also provide you with other ways to get in touch with the writer.
There used to be a day when you could create one generic resume and then blast it to a wide range of jobs you were interested in applying to. Even if you are using a resume service this practice of blasting is generally frowned upon. HR professionals are inundated with resumes and they want to see that applicants have read the ad and are responding directly to it. One-for-all type of resumes are easily spotted and are generally discounted by HR. So work with a resume service to see how you can best tailor yours for each job you are applying to.
Add in a list of skills Your resume is no place for modesty. Highlight your skills especially if they are specific to the job youre applying for and list where you gained experience with that skill set. Instead of being general give concrete details and highlights. For example list your experience with Microsoft Office or even a particular piece of software over computer skills. Make sure to include plenty of competency statements.
Avoid being vague If you have references include them. Dont say available upon request. If you have gaps in employment explain them clearly. They will probably come up in the interview anyways. Being prepared in advance by giving complete information in your resume is better than being caught off guard in the interview or worse skipped over all together.
Review the Job Posting and Description Carefully A lot of the time job-hunters will write one generic resume and send the same generic resume to every employer. This is one of the biggest mistakes facing job seekers because it produces so-so resumes that dont necessarily match the employers requirements.