there is no percentage that will work with the large rent variances that exist between the various markets.  

I'm thinking of strategies for rentals of my existing home.

Infill lots, minor subdivisions, or land with existing frontage and utilities will teach you more than any underwriting model.Also worth noting: lenders and equity partners don’t underwrite first-time developers on vision.

This actually adds you to the vendors insurance policy, whereas an insurance certificate only provides proof that coverage exists.

Overall, run the numbers with both short-term cash flow and long-term appreciation in mind before committing.

They can help you stay out of trouble you didn't know existed, and also stay focused on the aspects if your business that actually interest you.From the title of your post I see you are located in Ashburn.

Thanks for taking the time to help out a beginner.Drew You’re ALWAYS better off investing locally, where it’s easier to:Learn the marketNetwork to find dealsNetwork to find contractorsBe more hands-onDriveby property to keep tabs on itNetwork to find a decent Property Management Company (PMC)Next best location is somewhere else you lived, where you have an existing network of family & friends to help you as accomplish the above list as needed.If you invest OOS, your biggest challenge won't be finding properties to meet your goals on paper, it’ll be successfully outsourcing all of the above.The biggest mistake we see OOS investors making in our market, over and over again, is not fully understanding Neighborhood/Property/Tenant Classes and how they impact your probability of success!

You can also ask the seller for only what already exists, framed as a quick handoff rather than a demand.

And since most people have mortgages, and the sale is "subject to" existing liens you need to be very cautious. 

“If it’s borderline, don’t charge”This philosophy came up over and over.Reasons cited:Small deductions trigger disproportionate emotional reactionsDeposit disputes escalate faster than almost any other issueTime, stress, and legal exposure often exceed the money recoveredSeveral landlords explicitly said:Even when damage technically exists, we don’t charge if it’s close.4.