If you achieve permanent resident status by marrying an American citizen, you may be allowed to apply for citizenship after three years. You must show good moral character over the five year residency period. Basically, this means not getting into trouble with the law, with drugs, prostitution or alcoholism. You must be loyal to the United States and not have advocated the violent overthrow of the government. Formerly, membership in the Communist party of any country fewer than ten years before the date of application was suspect, though this is probably not as critical an issue as it used to be.
Any past wrongdoing involving visas and immigration matters can hamper the naturalization process.
In such cases, a lawyer may be necessary. You must show some English language abilities. These requirements are very simple. You will be asked some questions by the examiner about your application and made to read and write some simple sentences. Three to five years residence in the United States should be enough to learn some English.