Once you have selected your lender and gotten your pre-approval, you and your mortgage broker will not be finished.  The first thing your loan officer must do is build your loan file.  This means you will need to fill out a complete application and sign the many disclosure forms required by law.  While the paperwork may seem intimidating, none of it is binding.  You are not obligating yourself to anything.  You are merely authorizing your loan officer to work on your behalf. 

Depending on the kind of loan you are applying for, the loan officer will need to have you supply certain documents.  The traditional documentation will include two years W2s, current paystub, three months bank statements and statements from any other source of savings, personal wealth, assets or investments.  Other loan programs may require different documentation, or no documentation at all.  In general, the fewer documents you provide, the greater the risk to the lender and therefore the higher your payment.

Once your loan file is completed, it is submitted to the lending institution for underwriting.  Generally, they will issue an approval with conditions.  Your loan officer will be able to anticipate most documents needed, but rarely is everything in the file.  Once your file has been reviewed by the bank, you will often be required to produce new documents very quickly.  Sometimes these are as easy as your most recent paystub.  Sometimes they are lost documents that could take weeks to reproduce.

You may be asked to take care of certain problems that appear on your credit report.  Unfortunately, it is all too common for someone else's bad credit to end up on your report.  Your loan officer can advise you, but only you can fix these issues.  Work on them early and aggressively.  The credit bureaus make no money by helping you.  They will only comply with the bare minimum responses required by law.  The process of credit repair can be slow.  Don't take any of it personally.  Begin solving any problems as soon as you become aware of them.

Loan officers are human, and even the good ones sometimes fail to anticipate the needs of the bank.  Ask your broker what documents are likely to be requested that he doesn't already have.  It's better to have them and not need them, especially if they will take a couple weeks to receive them.  (Bank statements and replacement W2s are the most common missing documents that delay closing.)  Ask your loan officer what the possible surprises might be.  By being a good partner and working together, you and your mortgage broker can anticipate potential difficulties and clear them ahead of time.