One can become a lawful permanent resident in the U.S. based on different legal grounds, such as through family petition, employment visa, asylee or refugee status for at least a year, etc. Although the requirements and evidence one must submit differ from one category to the other, there are certain requirements that every adjustment of status applicant must comply with before his/her application for lawful permanent residence is approved.
Both the United States Citizenship and Immigration Services (USCIS) and the Immigration Courts have jurisdiction to grant a lawful permanent resident status, depending on the person’s status at the time of the application. The first and most important thing you must do if you would like to apply for a lawful permanent resident status is: to file a properly completed and signed Form I-485, Application to Register Permanent Residence or Adjust Status, along with other required civil and identity documents and, of course, a proof of your basis for applying for green card.
For example, if you are applying for green card based on an approved family petition, you must enclose copy of the approval notice from USCIS, or if you are applying based on some type of employment visa, you must similarly enclose the proof of approval or pending underlying petition that allows you to become eligible for permanent residency.
There are also instances where one is eligible to apply concurrent petitions of family or employment visas along with the Form I-485, in which case, you submit all forms and proof of eligibility together in the same application package. One example of these instances will be when a foreigner marries a United States Citizen, the law allows that person to apply for green card concurrently with the underlying family petition that the U.S. Citizen spouse will be filing.
Other important documents that are required to be submitted before one can get approved for a permanent resident status are medical evaluation forms, birth certificates and proof of lawful and inspected entry to the U.S. Like stated above, every application is considered for evidence on a case by case basis and it is always advisable to retain a knowledgeable immigration attorney to assist you in your application.
If you decide to apply on your own, the USCIS website has detailed instructions and applicable forms that you can download and fill out free of charge, but an experienced attorney can offer you peace of mind by ensuring that everything is done correctly the first time.