IF someone doesn't even have the money for an earnest money deposit then they are not likely to be able to pull off the deal.

Beginning with rent for the month of September, please pay your rent by depositing the entire amount into the following bank account at (your bank): account #123456; routing # 123456.

Then I require a double deposit, plus an additional fee to cover a mandatory, professional cleaning after departure.

If they opt not to accept the property by declining to timely give you a non-refundable reservation fee or actually sign the lease with a full security deposit and first month's rent THEN AND ONLY THEN should you process the next applicant.You should not process multiple people and select one subjectively; you're asking for trouble with fair housing when someone claims they were discriminated against.Offer the property to the first one that applies that meets your written standards for qualification.

As mentioned read your lease carefully.My lease states tenant is responsible for duration of lease or until It is rerented and they lose their deposit.

I just read chapter 16 (getting ready to close) in "The Book on Rental Property Investing" and it talks about keeping a checking account for rent and a savings for security deposits. 

We think the Buyer got cold feet and was afraid we were going to keep their deposit, so they ginned up a complaint.

@Theresa Harris - Good point....you can also deduct the window expense from her security deposit upon move out.

Ask her to schedule a final walk of the unit on or before (the departure date) with you so that you can arrange for any return of security deposit provided the unit is in satisfactory condition and all contents/trash are removed from the premises. 

That's why we also have a simple early termination for leases (1 month + deposit if there's no damages), because they get to walk clean and we get the property back, no fuss no muss.