#10. How to Check for Vacancy! - No, the apartment manager is not going to tell you that 40% of the units are vacant. Around 8 pm drive thru to see how many lights you see illuminated; how many cars are in the parking lot; if there are grills or chairs on the balconies or patios. Include your return address on your postcard and pay for first class postage. If units are vacant, the post office should notify you.