I start by telling them we have a lot of money tied up in the property, and we've been burned by folks that wanted us to believe the best of them. The result of those conversations? A lot of qualifying questions for any potential tenant.
Having said the above, I ask for some "standard" things, such as the names of everyone who'll be living at the unit. Anyone over 18 fills out has to furnish their social security and driver's license numbers, and pays a fee for a credit / background check. I ask if they are US citizens or green card holders, and I ask for past addresses for the past 5 years as well as any other names they used in the past (maiden name, nickname, etc). I take a picture of their driver's license.
I ask for phone numbers that accept texts and any alternate land or business phone numbers.
I ask for the names and birth dates of anyone under 18, and ask if there are any service / emotional support animals, together with their names and breeds.
I also ask for personal references, previous landlord contact info (and length of time there), employer contact info (and how long there, together with earnings), as well as the name and contact information for their manager / boss. Apart from the above contacts, I ask for an emergency contact.
Going still further, I ask for their social media handles to try to get a better handle on who I'm dealing with.
In the application, I ask if they smoke or vape. I ask them the number, make, model, and year of their cars. I also ask if they've ever been evicted, refused to pay rent, or filed for bankruptcy.
Further, I ask account numbers for their checking and savings accounts, and the approximate balances in each. I ask for a list of their current ongoing monthly expenses.
Lastly, I have them sign an authorization to check all the above with their bank, their employer, etc.
If the prospects look financially shaky or sketchy, I ask for the name of a co-signer - and collect payment for a background check on them.
Verbally, I also ask when they are interested in taking occupancy, and I tell them the application will be made part of the lease agreement - that I can evict them if they've lied in their application.
Good luck!