DO consult an attorney if you are contemplating accepting public benefits such as welfare or participation in the Aid to Families with Dependent Children program.  If the USCIS has reason to believe that you have become a "public charge," you could lose your green card.

THE DON'Ts

DON'T commit any crimes.  Your green card will not keep you from being deported.

DON'T engage in politically subversive activities. 

DON'T smuggle other foreign nationals into the United States.

DON'T charge others for legal advise.  Even though your experience of obtaining a green card may have made you an expert, it is not legal to practice law without a license.

DON'T create the impression that you are not living in the United States once you have obtained your green card.  If you leave the United States for too long, you may lose your green card.

DON'T lie on any USCIS form.

DON'T lie to USCIS officers.

DON'T leave parts of your forms blank, or assume that a part of the form is unimportant.  If the information really does not apply to you, insert "N/A" or "none."  For example, if you are not married, you should put an "N/A" on the portions of the forms asking for spousal information.  But if the form asks for your addresses for the past five years, you must supply complete addresses with no time periods unaccounted for.

DON'T open the envelope with your medical exam results in it.  If you want to see the results of your exam, most physicians will supply you with a copy.