No sample resumes are accessible. A competent resume writing service will provide a number of samples for review. You can assess the quality of their work only if have these samples. If there are no samples available on their website ask them for the specimens of their work. If they are unable to provide satisfactory examples of their work you had better opt for another service.
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.
Focus on achievements Employers not only want to know what you have done in the past they also want to know where you have excelled. If you have awards achievements or on the job highlights make sure to add them. If you were part of a team you were part of the success. If your project increased production by 20% and you played a part in it add it on your resume!
Be honest Never lie or stretch the truth on your resume. If your employer finds out later you will probably be terminated. If your resume is lacking in some areas build those areas up honestly by increasing your skills instead of pretending. The truth will always come out eventually and it usually hurts you in the end.
Functional format is best for those who are switching their career or have large employment gaps on their resume. In this format, you dont have to list the joining or resigning dates of the previous employments. Functional format will hide your employment gaps or your job switching.