When looking at SFRs so many will never cash flow. If a property is not in a realistic ballpark it is usually not worth analyzing. Knowing the seller's circumstances is very important as well.
I also like to keep in mind my goal for investing in the property. How long do I intend to hold onto this deal? How will I finance it (equity, debt or a mixture of both)?
When I'm analyzing a deal I want to know projected income and expenses. In my area it is easy to verify property taxes and I have a good insurance agent that that I talk and as a result have a good working knowledge of what they cost will be in my area. When I inspect the property I can usually get a feel for what deferred maintenance exists as well as what it would approximately cost to make the place rentable.
This gives me much of the costs. I then look at area vacancies, economic conditions, employment opportunities, area demographics and verify that the property has not been red tagged or have any other underlying problems that might make it difficult to resell or rent.
When I have my financial information then I can consider debt service and costs related to equity partners in the overall income produced. If i am holding onto this property for a definite period of time, I also will want to calculate the IRR to see how it stacks up with other potential investments that I have run into.