I would recommend that you start creating a document containing your life data now. There are certain areas on the applications that you will have to complete. Making sure everything is accurate is important.
Education—Applications will ask for each school's location and the dates of attendance. If you moved about as a child, this may require some research: Do it now. You will need information about your college or other tech schools, including their proper location, the number of hours you accumulated, your major, and degree or certifications obtained.
Work History—Applications will inquire as to where you have worked in the past. Correct dates of employment, beginning and ending salary, and names of supervisors will be expected. Have the proper phone numbers for contact as well. One important point is to honestly answer the reason for leaving the employment. The background investigator will find out, so be honest.
References—Have their proper names and titles. Do not put down "Slim," "Sport," or "Bubba" unless, of course, these are their true birth names. Accurate mailing addresses and contact telephone numbers are a must. If you're providing a person's mobile phone, work, or home number, so note it. Also, it is proper for you to request permission for someone to actually serve as a reference for you. The big warning here is that a very astute background investigator will chat-up a reference about you. But, their question will be to 'give me three other people that know about you.' This is where the investigation takes a twist.
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