The most important thing to remember when filing an immigration petition or application is candor and thoroughness. Failure to do so may result in delay or the ultimate denial of your application. It is crucial that you disclose ALL of the information, that USCIS is asking for. Besides simple disclosure, it is also important to explain as thoroughly as possible. For example, if they USCIS asks about your criminal history, it is critical that you disclose EVERY arrest or incident, no matter what the outcome of the incident was. If your case was dismissed, sealed, expunged, etc., be sure to include that in your explaination. It is also advisable that you attach applicable documents to your application, which provides proof to the statements you are making.
A major critieria in the immigration process is the USCIS's "perception" of the truthfulness of the applicant. Whether this preception is true or not, it is what they will be basing thier decision on. If you provide them any reason to believe that you are less than truthful in your application, they can deny it solely based on on that. Although most ommissions of information are not intentional, having to explain those mistakes later can be quite burdensome.
It is imperative that an applicant thoroughly reviews his/her application before submission. Once it is submitted, can retractions or oral modifications (at interviews) can be construed as not be truthful.
James C. Tai