File a Request for Notice
You need to know what is happening in the case and get on the mailing list. If you have hired creditor's counsel, they will do it.
Get a PACER account.
Most federal courts are on electronic filing now so having access to the PACER database is critical. There is a small charge, but worth the information.
Appraise the Property
Know type of equity position you have, it will determine whether you have grounds to seek relief from the automatic stay to foreclose on the collateral for your loan.
File a Proof of Claim and Go to the Meeting of Creditors
There are strict deadlines, and those published in the Notice of Meetings of Creditors. The meeting of creditors is your opportunity to ask questions about the debtor's financial condition. Take the opportunity while they are under oath to ask them about how they plan to deal with your debt. Are you going to list the building for sale? Take in a tenant? Re-finance?
Hire Creditor's Counsel.
Certain bankruptcy filings like a Chapter 11 can be incredibly complex. In both a Chapter 13 or 11, the debtor will propose a plan for reorganization that could be detrimental to your loan. You will need to file an objection or engage an attorney to scrutinize the plan and fight it if necessary. In some cases, creditors can propose the plan after the debtor's exclusivity period ends. Your attorney can also assist you in getting your motion for relief on file or otherwise counsel you on debtor's attempt to lienstrip.