A pre-approval is a mandatory item you will need to being looking at homes. It is a requirement before myself or any Agent will help you... at least the top produces. Without a pre-approval neither you or I know what you can actually do financially. So if you're wanting to purchase a home this is actually the first step. And the best way to be prepared for the is know what you need.
Here are a few pointers when filling out the application that would be helpful.