the number of people permitted in that size duplex, that you screen for credit score of xxx or over, verifiable income source, and you verify housing references, and if that works for them you'd like to set an appointment up for showing your showing apartment on >>> date betweeen >>>and >>>.Meet them, show them the  apartment have application ready for them to fill out with ID you can verify.Why anyone would expect someone to do an applicaion with fee's prior to seeing the unit or verifying in advance that their ID matches to whom is applying is rather ODD.I've had people apply that couldn't come in person,, moving from out of state.. and I required copy of photo ID, application fee's via overnight mail.. and its worked but average is phone info, meet, show, apply, process application.Have your lease and documents ready, per your state law requirements. 

Obviously screening the potential clients is key, but I have had good results.

The seller wasn't a very good landlord as he let one bad tenant past his screening and 2 more tear the place up.

What is the minimum credit score you require when screening for potential tenants?

Might have it's on pool, indoor pool nicer, great rec room/theater room (not just a theater chair and a big tv).  1-bedroom - $175-$250 a night 2-bedroom $230-$400+ a night (an indoor pool can get you anywhere from $75-$200 more a night). 

Or, possibly their client has failed to pass other landlord screenings causing desperation. 

I have actually been working on an Excel sheet that includes depreciation recapture and the effect on your profit on the property. i attached part of a screen shot, i am still working on it ( off and on) but what i have come to figure is that there is a time when it is best to sell the property, otherwise you do start losing money.( unless you keep it and have it passed to your heirs). the sample i have on there is a house bought for 110K / 90K loan, as you see the yellow highlight is on a cell that reaches a tipping point on when your income, taxes and depreciation recapture tax / closing costs, would start to "cost" money - you would not make as much upon sale of the property. and i broke it down to 27 years, didn't see a need to have that 1/2 yr in the model.I also have it to where if you add to the asset ( addition, etc) it will add to the basis and change the numbers, but like i said there are still things i want to work out more and add.this does not include cost segregation as @Jay Hinrichs,@Jeff Glass,@Eamonn McElroy,@Barry Ruby and @Yonah Weiss have mentioned this is just a straight depreciation on a residential property.

When I first started I had no clue how to do a contract, how to screen tenants, or how to advertise the properties.

Here are some screen shots of how I CUSTOMIZED QuickBooks that worked for me. 

Then pre-screen all applications and discard the ones that do not meet minimum requirements.