It's a good idea to have your phone screening questions well thought out in advance and written down. Pay attention to non-discrimination laws. We do a quick eight question screening that weeds out most undesirables and people who don't meet our minimum criteria. (5-10 minutes) If they pass that, then we follow-up with a pre-qualification interview of about 20 questions. (15 - 30 minutes) If they pass that, then we show the property.
At the start of the interview, I ask for the full legal name of all adults who will be residing at the place. While we are talking, unbeknown to them, I look them up in the Unlawful Detainer book published by our local rental association and I peruse the Washington Courts website.
Up front (in our advertising and in our first contact by phone) we let people know we value open and honest communication and that we will do a thorough background check of rental history, income history, credit history and legal history. Not too amazing, we rarely have an applicant who lies to us on their application. The liars usually self disqualify and don't get to the application phase.
Applications, written rental criteria, and a property info sheet are available at the time of showing for prospective tenants to take with them. While I am showing the property, I am evaluating them further by observing what they do, what they say, and what I see (their demeanor, their appearance, their car.) I pay attention to the red flags and to my intuition. When I take the application and application fee, I ask the prospective tenant to contact their references to let them know to expect a call from me, so I can process their application more quickly. The applicants who give false information may reveal themselves when they see I am serious about reference checking.
I process one application at a time. The first thing I do is review the application in front of the applicant to make sure all questions are answered, that the application is complete, to clarify ambiguities, and to check photo ID. Then I start with the internet, checking the validity of addresses and phone numbers for employers and previous residences. I also google the applicants name and check out social media sites (My Space, Face Book, LinkedIn, etc.). Then I call references and do the other necessary background checks. Some are done through a service we hire.
Regarding your findings, do not write any notes or change anything on the application itself. Use a separate sheet for notes, as the application, if falsified by the applicant, becomes evidence. If I reject the application, then I mail an "Adverse Action Notice" as required by Washington State law that explains the reason for denial.
Eighteen years as a rental property owner and manager (3 houses and 6 duplexes) has taught me how to quickly ascertain if a person is a likely candidate. I prefer to disqualify them (respectfully and gently) as soon as I know they will not meet our minimum criteria, then I give them other resources for them to pursue and wish them well. I save my time and energy for the good prospects.