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.
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 Sample When you are referring the online resume samples, you will need a functional sample if you have employment gaps in your past. Functional format does not draw attention towards the gaps in employment history of the applicant. Rather it focuses on the existing skills of the applicant. It will explain to the employer about how these skills can help to benefit the company.
No contact address is available. If the service does not have a physical location they may not be a suitable option for you. The chances are they are more into mass production of average documents. Numerous resume mills employ non-skilled individuals overseas to create these documents. They get hold of your current resume embellish it with the information available from the questionnaire and place it in a standard format.
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.