U.S. immigration is a complex process often involving multiple federal agencies when, if done incorrectly can have a life changing effect on the future of the applicant, the applicant's family and employer. The immigration process requires understanding of the law, a strong knowledge of the process and the skill to apply the facts of any particular immigrant's situation to a rather rigid set of criteria.
However, in the U.S. one does not need to be a licensed attorney in order to give immigration advice or to assist in filling out forms. So called, immigration consultants or immigration services, often found in ethnic neighborhoods attached to a travel agency or other store front, are a ready source of cheap consultants who will help you fill out forms for about $50 but often provide incomplete or worse, bad advice and direction with the consequence that an application or petition is denied. My office has seen many cases where a client has been misinformed by a consultant, denied approval and as a result, fallen out of status or worse found themselves in deportation proceedings, even though they had a legal basis for remaining in the U.S. and getting approved.
Reliance on these services is a mistake. Why put your lawful future and the future of your family at risk by relying on unlicensed, unregulated and often-misinformed consultants for the sake of saving a few dollars? Spend the time and effort to find a reputable attorney or legal service that knows the law. A good attorney should get it right the first time; each and every time. If the facts of your case present challenges that could lead to a denial, this should be explained to you in advance.
The USCIS and the immigration process do not have much tolerance for mistakes and zero tolerance for lies or misrepresentations. Hire a competent professional. Hire an attorney. After all it's your future in America that is at stake.