The best bet is to just call the buildings that your friends and family work in and say"Hi I am Greg Crowley(use your name) and I am going to be doing work in your building or for so and so in your building on the 12 of april I was wondering since I am going to be in the area can I give you an estimate? I know you may not need a cleaning right now but I would give you a quick evaluation and you can decide from there If you have an empty unit I would love to clean that for the onsite manager to evaluate so there is no risk to you. No one wants a long sales pitch ask if they have questions and if they don't want you ask if you can send your info.
I have been in the apartment business a long time and the best way to get the complexes is absolutely cold calling and passing out cards having a magnet and a price sheet and coffee mugs is great it shows creditability to show your not a fly by nite guy!